RECIPROCAL EFFECTS OF CONCOMITANT INFECTIONS : I. THE INFLUENCE OF VACCINIA ON THE REACTION TO INFECTION WITH EXPERIMENTAL SYPHILIS.

Experiments are reported in which was studied the effect of a concomitant infection, vaccinia, upon the syphilitic reaction of rabbits. Vaccine virus was inoculated intracutaneously on the side of the body at the time of intratesticular inoculation with Treponema pallidum. The results showed clearly that the vaccination caused a profound disturbance in the syphilitic reaction, the ensuing syphilis being extremely severe. From an analysis of various features of the reaction, it appeared that the factor of host resistance was primarily concerned in the effects observed.     

RECIPROCAL EFFECTS OF CONCOMITANT INFECTIONS : II. THE INFLUENCE OF VACCINAL IMMUNITY ON THE REACTION TO EXPERIMENTAL SYPHILIS.

Experiments are reported in which it was shown, first, that the effectiveness of the reaction to experimental syphilis was increased in rabbits immune to vaccine virus, the ensuing disease being less severe than in control animals. It was further shown that a comparable modification of the syphilitic reaction occurred in rabbits inoculated intratesticularly with a mixture of Treponema pallidum and vaccine virus, and it was suggested that this result was due to the influence of a vaccinal immunity and to the local effect of the vaccinal reaction. It was pointed out that the manner in which two concomitant experimental infections are induced is of significance in determining the character of the host''s reaction.     

FURTHER OBSERVATIONS ON THE RELATION OF THE EYE TO IMMUNITY IN EXPERIMENTAL SYPHILIS : II. THE DEVELOPMENT OF IMMUNITY AFTER PRIMARY INTRACORNEAL INOCULATION

Two experiments are reported in which an attempt was made to determine the extent to which a primary syphilitic infection of the cornea in rabbits is followed by the development of a local corneal immunity, by the generalization of the virus, and by the development of a general immunity to the infection. Female rabbits were inoculated intracorneally with a virulent strain of T. pallidum and the disease was allowed to run its course until the lesions which had developed at the site of inoculation had healed spontaneously. Popliteal lymph nodes were transferred from about one-half of these animals (in the second experiment only) to normal male rabbits and in almost every instance the nodes were proved by this method to contain virulent treponemes, showing that generalization of the syphilitic infection is the rule after intracorneal inoculation. All animals were treated with arsphenamine after the local lesion had subsided (160 and 275 days after the original inoculation). The rabbits were then reinoculated with the homologous strain of treponemes, injections being made into the cornea originally inoculated and also into the skin of the back. In one experiment both corneas were reinoculated. The incidence of lesions developing in either cornea after reinoculation was higher than the incidence of lesions developing in the skin. The lesions developing in the corneas of the "immune" animals had a longer incubation period and were of shorter duration on the average than the lesions in the control group. As far as intensity of reaction was concerned no difference was observed. Inoculation of the cornea of rabbits with syphilitic virus is often followed by the development of immunity to the homologous strain of organisms. This immunity is imparted to the skin to a greater extent than to either the cornea inoculated originally or to the opposite uninoculated cornea. It persists after treatment with arsphenamine. It appears to be more marked the longer treatment is postponed. It is apparent from Table IV that in one-half of all the test animals both cornea and skin were immune to a second inoculation of homologous syphilitic virus. In addition to these there were 5 animals in which the cornea was immune and the skin nearly so, for the lesions which developed in the skin of these animals were minimal in extent and duration and were in no way comparable to those which were observed in the controls. Thus in two-thirds of our animals there developed in both the skin and the cornea, after a primary intracorneal inoculation, a high degree of resistance toward a second inoculation with homologous syphilitic virus, but syphilitic disease of the cornea does not always impart to the cornea itself an absolute immunity to reinoculated homologous virus.     

FURTHER OBSERVATIONS ON THE RELATION OF THE EYE TO IMMUNITY IN EXPERIMENTAL SYPHILIS : III. THE INFLUENCE OF A NON-SPECIFIC INFLAMMATORY REACTION IN THE CORNEA ON THE DEVELOPMENT OF IMMUNITY IN THAT TISSUE AFTER INTRATESTICULAR INOCULATION

Two experiments are reported in which rabbits originally inoculated with syphilis and treated late in the course of the disease (174th to 210th day) were reinoculated subsequently in both corneas with the homologous strain of syphilitic virus. In each animal one cornea was inoculated with dead tubercle bacilli prior to reinoculation with the syphilitic virus. This procedure was carried out in order to bring about a non-specific inflammatory reaction with resultant vascularization, the intention being to find out if such vascularization would render the cornea more resistant to inoculation with the homologous strain of syphilitic virus. The results of both experiments were similar and while they were not conclusive, they indicated that there was a tendency for corneas which had been injected with dead tubercle bacilli to be more refractory to a subsequent inoculation with homologous syphilitic virus than the corneas of the same animals that had not been injected with dead tubercle bacilli. This tendency may be interpreted as suggestive evidence for the view that in the syphilitic rabbit there develop circulating antibodies toward the homologous strain of T. pallidum.     

EXPERIMENTAL OBSERVATIONS ON THE "CURE" OF SYPHILIS IN THE RABBIT WITH ARSPHENAMINE

1. The intravenous administration of six doses of arsphenamine to syphilitic rabbits in amounts of 10 mg. per kilo, 127 days after inoculation is sufficient to render the popliteal nodes of such animals incapable of transmitting the infection to normal animals. 2. Syphilitic rabbits that have been treated in this manner and whose popliteal nodes 32 to 38 days after treatment have been shown to be incapable of transmitting the infection to normal animals are, as far as can be judged by the absence of a local lesion, refractory to a second inoculation of active virus of the same strain, if the inoculation be made intradermally at the base of the ear and carried out 209 days after the first inoculation. 3. Untreated syphilitic rabbits are also refractory toward a second inoculation made in a similar manner and at a similar interval following the first inoculation. 4. Evidence is offered in favor of the view that the most satisfactory method of evaluation of antisyphilitic agents in experimental syphilis of the rabbit is that of lymph node transfer. 5. Evidence is offered in support of the view that the state of refractoriness toward a second inoculation exhibited by syphilitic rabbits may be explainable upon the basis of either an acquired immunity or persistence of a focus of living treponemata in the body.     

A STUDY OF THE RELATION OF TREPONEMA PALLIDUM TO LYMPHOID TISSUES IN EXPERIMENTAL SYPHILIS

A widespread dissemination of Treponema pallidum from a local focus of inoculation in the rabbit constantly occurs by way of the lymphatics. Spirochetes were regularly recovered from the satellite lymph nodes by animal inoculation after scrotal inoculation; they were present as early as 2 days, when no specific primary reaction was detected, and at later periods of from 5 to 61 days after inoculation. Other superficial nodes at remote sites such as the popliteals and with no syphilitic lesions in the drainage area have also been shown to harbor active organisms. Although spirochetes were found in relatively few of the lymph node emulsions, the orchitis resulting from their injection was of a rapidly progressive type with an incubation period but slightly longer than that produced by a testicular or skin nodule emulsion rich in spirochetes. It has further been shown that a syphilitic infection is sufficiently established in the rabbit body within 48 hours after scrotal inoculation so that the primary lesion is no longer essential for its maintenance. Active treponemata survive in the popliteal lymph nodes for long periods of time and have been regularly recovered from them in cases of true latency. The lymph nodes, therefore, function as reservoirs of the organisms. The ability to recover the spirochetes from lymphoid tissue through successive generations is seen in the serial passage of lymph node emulsion to testicle during an 18 months period. The persistence of spirochetes in lymphoid tissue irrespective of the presence or absence of syphilitic lesions is a characteristic and fundamental feature of syphilis of the rabbit. The existence of infection, therefore, may be demonstrated at any time by the recovery of spirochetes from the popliteal lymph nodes by animal inoculation. This fact is of great practical importance in the therapy of the infection and may be profitably utilized in determining the ultimate effect of a therapeutic agent. These experiments demonstrate that the disease is not confined to the site of local inoculation but that lymphogenous dissemination of treponemata regularly takes place, and that during the course of this process organisms become localized in the lymph nodes and exist there indefinitely irrespective of the occurrence of manifestations of disease. The intimate relation of Treponema pallidum to lymphoid tissue is an essential concept of syphilis of the rabbit, and from this point of view, the infection is primarily one of lymphoid tissue.     

RELATION OF THE SIZE OF THE INOCULUM AND THE AGE OF THE INFECTION TO THE CURATIVE DOSE OF PENICILLIN IN EXPERIMENTAL SYPHILIS,WITH PARTICULAR REFERENCE TO THE FEASIBILITY OF ITS PROPHYLACTIC USE

1. A relatively small amount of penicillin sufficed to abort syphilitic infection in rabbits when administered during the incubation period of the disease. 2. The abortive dose, given as a single intramuscular injection in oil and beeswax, varied with the age of the infection. (a) With a fixed intratesticular inoculum, the amount of penicillin necessary to prevent infection in half the animals remained at a constant level for 4 days. By the end of the 2nd week more than seven times this dosage was needed; and by the 6th week, after the chancre had appeared, more than thirty times the amount was needed to obtain the same result. The progressive increase in the abortive dose of penicillin with the passage of time probably reflects the interim multiplication of organisms. (b) Qualitatively similar results were obtained in rabbits inoculated intracutaneously. 3. The abortive dose varied also with the size of the inoculum. In animals inoculated intracutaneously with 20, 2,000, and 200,000 spirochetes, and treated 4 days later, it required 200, 500, and 3,500 units per kg., respectively, to protect half the animals, and the corresponding PD₉₀ dosages were 500, 2,000, and 16,000 units per kg. 4. The present observations, indicating the ease of aborting experimental rabbit syphilis during the incubation period by a single injection of penicillin, are perhaps applicable to the prevention of the disease in man. 5. Asymptomatic infections were rare in animals receiving inadequate doses of penicillin during the incubation period. Sixty-four of sixty-five such animals developed darkfield-positive lesions at the inoculated site. In animals treated 6 weeks after inoculation, however, after the development of lesions, inadequate treatment was usually manifested by an asymptomatic redissemination of organisms demonstrable only by lymph node transfer. The difference in the two groups probably reflects the beginning development of immunity in the rabbits treated 6 weeks after inoculation. 6. As suggested by Rake and Dunham (11), the treatment of animals during the incubation period permits a rapid assay of antisyphilitic agents, and one which requires only small amounts of material. Possible limitations of the method are discussed in the text.     

A CUTANEOUS REACTION IN SYPHILIS

1. I have proposed the name luetin for an emulsion or extract of pure cultures of Treponema pallidum which is designed to be employed for obtaining, in suitable cases, a specific cutaneous reaction that may become a valuable diagnostic sign in certain stages or forms of syphilitic infection. 2. The repeated inoculation of either living or killed pallida into the testicles of rabbits leads to a condition in which an intradermic injection of luetin is followed by a well marked inflammatory reaction. A corresponding reaction has been obtained neither in rabbits suffering from active syphilitic orchitis, nor in those in which the condition had been cured by the administration of salvarsan four months previously. Normal rabbits, likewise, do not react to the luetin. 3. The luetin produces a similar cutaneous reaction in syphilitic and parasyphilitic patients that is most constant and severe in the tertiary and hereditary affections. In my series of cases, it was present constantly (100 per cent.) in the manifest tertiary affection, in 94 per cent. of latent tertiary affection, and in 96 per cent. of the hereditary affection. 4. During the primary and secondary stages, the reaction is infrequent, and when present it is of mild degree. An exception has been found in cases in which energetic treatment has been or is being carried out and in which clinical signs of syphilis are absent. Such cases may show a severe reaction. Apparently this is true especially of the cases treated with salvarsan. 5. In certain cases of old infection in which no treatment has been taken and in which no symptoms have appeared for many years, and in the course of which miscarriages have not occurred, the cutaneous reaction has failed to appear. But, despite the absence of symptoms, mothers who have young syphilitic children have usually given the reaction. 6. It remains to be determined in how far the cutaneous reaction with luetin can be used to supplement the Wassermann reaction in determining the complete and permanent suppression of a syphilitic affection. 7. It appears probable that the Wassermann reaction is more constant in the primary and secondary, and the cutaneous reaction in the tertiary and latent forms of syphilis. Moreover, it appears that the Wassermann reaction is more directly and immediately affected by antisyphilitic treatment than is the cutaneous reaction. 8. A more active preparation of luetin can certainly be produced by improved methods. This phase of the subject is being considered at the present time and will be reported upon in a later paper.     

STUDIES IN EXPERIMENTAL SYPHILIS : VI. ON VARIATIONS IN THE RESPONSE OF TREATED RABBITS TO REINOCULATION; AND ON CRYPTOGENETIC REINFECTION WITH SYPHILIS.

Syphilitic rabbits inoculated intratesticularly and treated with arsphenamine before the 69th day of the disease, when reinoculated with the same strain of treponemata and in a manner identical with that of the first inoculation) are capable of responding to the infection in at least five different ways. In addition to exhibiting a local lesion at the site of reinoculation, accompanied by dissemination of the virus, they may show no local lesion at all but present evidence of dissemination of the virus together with the development of a positive Wassermann reaction. In some instances the virus may be recovered from the reinoculation site although no local lesion is produced there and no dissemination of the virus can be shown to take place. An occasional animal treated before the 69th day of the disease remains completely refractory to a second infection. When treatment is postponed to 6 months or more after the original inoculation, reinfection carried out by intratesticular injection is almost always impossible and such animals appear to be entirely refractory. However, if rabbits treated late are reinoculated with the homologous strain by depositing the virus upon a granulating wound on the back, successful reinfections can be accomplished in at least 50 per cent of the test animals. The resistance which develops in rabbits in the course of syphilitic infection is, then, not absolute but relative. It is pointed out that these results cast discredit upon the validity of the reinoculation method as a test of cure in syphilitic infection. It is also suggested upon the basis of these experiments, that the subsequent occurrence of a positive Wassermann reaction in patients with early syphilis in whom the Wassermann reaction has become negative under treatment may not always represent a relapse in the the disease but possibly in some instances a new infection without clinical signs.     

STUDIES BASED ON A MALIGNANT TUMOR OF THE RABBIT : II. PRIMARY TRANSPLANTATION AND ELIMINATION OF A COEXISTING SYPHILITIC INFECTION.

Several attempts were made to transplant a spontaneous malignant tumor in a syphilitic rabbit before a method was devised which proved successful. Subcutaneous and intracutaneous inoculations were unsuccessful on account of the vigorous granulomatous reaction which was aroused by the introduction of tumor fragments into these tissues. This difficulty was overcome by the use of intratesticular inoculations. With this method, a good growth was obtained in practically all animals. It appeared possible, however, that a syphilitic infection had been transmitted along with the tumor, and hence treatment with arsphenamine was instituted as a means of eliminating this infection. A study of the transplanted tumor in the first and second generations showed that it possessed a high degree of malignancy. Metastases occurred at an early period in the majority of animals, and while some of them appeared to recover, the indications were that more than 50 per cent might be expected to succumb to the effects of the tumor growth within a period of 6 to 7 months. The method of intratesticular inoculation now in use is described in detail.     

THE BUTYRIC ACID TEST FOR SYPHILIS IN THE DIAGNOSIS OF METASYPHILITIC AND OTHER NERVOUS DISORDERS

1. In the secondary and tertiary stages of syphilis without direct involvement of the nervous system the cerebro-spinal fluid yielded the butyric acid reaction of feeble intensity. The fluid under these conditions gave neither a positive cytodiagnosis nor the Wassermann test for syphilis. 2. The cerebro-spinal fluid of cases of hereditary syphilis showed a positive butyric reaction in about 90 per cent. and a positive Wassermann test in about 80 per cent. of the cases examined. 3. The cerebro-spinal fluid of cases of cerebral and spinal syphilis yielded the butyric acid reaction and the cytodiagnosis in every instance (100 per cent.) and gave the Wassermann reaction in from 50 to 75 per cent. of those examined. 4. The cerebro-spinal fluid from cases of general paralysis gave positive butyric acid reactions in 90 per cent., positive cell counts in 91 per cent., and positive Wassermann test in 73 per cent. of those examined. 5. The cerebro-spinal fluid from cases of tabes dorsalis gave positive butyric acid reactions and cell counts in 100 per cent. and positive Wassermann test in 53 per cent. of those examined. 6. The cerebro-spinal fluid from other forms of psychosis in which a syphilitic history was not obtained gave positive butyric acid reactions and cell count in 2.8 per cent. and Wassermann test in 13 per cent. of those examined. 7. The cerebro-spinal fluid from cases of acute inflammatory diseases of the meninges always gave a flocculent precipitate with the butyric acid reaction but never gave the Wassermann test. 8. The cerebro-spinal fluid from persons suffering from typhoid fever, pneumonia, pulmonary tuberculosis, etc., in which the meninges are not inflamed, gave neither the butyric acid nor the Wassermann test. 9. We think it justifiable to conclude that the butyric acid reaction affords a ready means of distinguishing normal from pathological cerebro-spinal fluid and will prove to be useful in routine clinical practice, especially in detecting syphilitic disease and in confirming or setting aside certain doubtful diagnoses of syphilitic or metasyphilitic lesions of the central nervous system. The reaction should commend itself as a valuable addition to the Wassermann test, the results of which it is capable of confirming and extending.     

STUDIES ON TREPONEMA PALLIDUM AND SYPHILIS : V. FURTHER STUDIES ON THE RELATION OF CULTURE PALLIDA TO VIRULENT PALLIDA AND ON REINFECTION PHENOMENA.

1. Immune sera produced in rabbits by treatment with our Culture Strain A of Treponema pallidum agglutinated not only the homologous strain, but also the Noguchi strains, and indicate a close group relationship of other non-pathogenic treponemata. Absorption experiments confirmed this, indicating a close relationship between the pallidum and the calligyrum. 2. Culture treponemata are not agglutinated to a much greater extent by the sera of syphilitic rabbits than they are by those of normal rabbits. 3. Culture treponemata are not agglutinated to any considerable extent by the sera of rabbits immunized with virulent treponemata. 4. The sera of syphilitic patients, especially those in the tertiary stages, agglutinate culture pallidum to a slightly greater extent than do those of normal individuals, but the culture pallidum is agglutinated to an almost equal degree by the sera of many individuals with diseases other than syphilis. We do not think that we could definitely distinguish the syphilitic from the non-syphilitic serum by the agglutination of the culture pallida, and therefore we do not believe that the reaction has any diagnostic value at present. 5. Immunization with culture pallidum, either general or local, does not seem to confer upon rabbits any considerable degree of resistance to inoculation with virulent treponemata. 6. Rabbits that have once exhibited lesions in the testis are not easily reinfected at the same site if reinoculation is practiced more than a month or so after apparent healing of the lesion. We believe that the experiments above recorded strongly suggest that resistance to syphilis in rabbits is a localized cell phenomenon not dependent upon a generalized reaction on the part of tissues remote from the site directly involved in reaction with the invading treponemata. Antibodies analogous to those formed in most bacterial infections appear in the general circulation in slight amount, if at all. The finding of many motionless treponemata in a few of the small lesions following reinoculation suggests the possibility of a purely localized formation of antibodies. This was expressed by Landsteiner some years ago when he spoke of the localized formation of agglutinins when they were absent in the general circulation. We hesitate to apply these results too generally to the conditions prevailing in human syphilis, but they contain the possibility of an explanation for the apparent skin immunity of the secondary period, and the later successive involvement of some organs and tissues when others remain normal and when external superinfection is successfully resisted.     

INFLUENCE OF TEMPERATURE UPON THE VELOCITY OF THE COMPLEMENT FIXATION REACTION IN SYPHILIS

Examination of syphilitic serum or cerebrospinal fluid can be made at any temperature between 23° and 37°C. The velocity of the fixation reaction, including the fixation of complement and subsequent hemolysis, is greater at a higher temperature, the optimum point being 37°C. The maximum reaction is also reached, however, when the mixture of lipoids, syphilitic serum, and complement is allowed to stand for a long enough period at a lower temperature, the minimum thermal point being near 23°C. For the optimum temperature (37°C.) an incubation of 30 minutes is sufficient, while for the minimum temperature (23°C.) 2 hours are necessary. At the temperature of 30°C. the reaction proceeds with moderate velocity and is complete within 60 minutes. Guinea pig complement gave a sharper reaction with the sera which contained less than one unit of the fixing substance. Fixation is complete, however, at any of the three temperatures within 20 minutes when there are more than two units present. A serum containing one unit of fixing substance will complete reaction within 30 minutes at 37°C., 60 minutes at 30°C., and 2 hours at 23°C., irrespective of whether human or guinea pig complement is used. For many reasons a properly adjusted thermostat for 37°C. is recommended for conducting the serum diagnosis of syphilis when possible, but it should not be overlooked that at a temperature near 30°C. an entirely reliable result can be obtained without a special incubator. Even at a temperature as low as 23°C. the test can be carried out if sufficient length of time is allowed. The foregoing conclusions refer only to the systems in which the acetone-insoluble fraction of tissue lipoids is used as antigen.     

STUDIES IN EXPERIMENTAL SYPHILIS : VII. REINOCULATION OF TREATED AND UNTREATED SYPHILITIC RABBITS WITH HETEROLOGOUS STRAINS OF TREPONEMA PALLIDUM.

Syphilitic rabbits, whether untreated or treated after the 90th day of infection, were found to be more refractory to subsequent inoculation with the homologous strain of Treponema pallidum than to inoculation with heterologous strains of the same organism, when clinical criteria alone were employed in judging the outcome of reinoculation. The incidence of second infection with homologous strains was 5.4 per cent, as against 50 per cent with heterologous strains.² The resistance which develops in rabbits during the course of a syphilitic infection appears therefore to be strain-specific rather than species-specific. The protection afforded against homologous strains was found to persist for at least as long as 6 months after treatment was discontinued. A given strain may afford a higher degree of protection against some strains than against others, but whether this is to be explained upon the basis of biologic relationship or of differences in virulence, or possibly as the result of both of these factors was not disclosed by the experiments. Rabbits infected with a strain (Nichols) which had been adapted to this species for over a decade could be infected with strains which had been recovered recently from the human body. The previous existence of a syphilitic lesion in the testis which was used as the site for reinoculation did not seem to exert any influence upon the incidence of successful second infections obtained with heterologous strains of Treponema pallidum. Sometimes the course of the second infection produced by inoculation with heterologous strains was less pronounced than that observed in the controls, but in most instances no significant alteration was observed. In syphilitic rabbits treated late in the course of the disease and reinoculated with heterologous strains of Treponema pallidum no lesion may develop at the site of reinoculation but nevertheless the Wassermann reaction may become positive and remain so for weeks thereafter. It is suggested that such animals may be examples of asymptomatic reinfection.     

STUDIES ON THE PHYSIOLOGICAL EFFECTS OF FEVER TEMPERATURES : IV. THE HEALING OF EXPERIMENTAL SYPHILIS LESIONS IN RABBITS BY SHORT WAVE FEVERS

1. Multiple, unsustained fevers (41–42°C.) produced by irradiation in a high frequency electrostatic field (10,000 kilocycles) destroyed T. pallidum in rabbits with active syphilitic lesions as determined by the injection into normal rabbits of extracts prepared from their testes and popliteal lymph nodes. 2. One febrile period of 6 hours at a temperature of 41.5–42°C. was likewise found to be sufficient to destroy T. pallidum. 3. Infection with T. pallidum persisted in a control series of untreated rabbits for as long as 395 days after inoculation, but clinical healing occurred in from 3 to 4 months after injection. 4. The time interval between inoculation and fever treatment, or between the end of the fever treatment and reinoculation, did not affect the results. 5. The fever treatment was effective at any stage of experimental syphilis in rabbits.     

THE OCCURRENCE OF STIGMATA OF CONGENITAL SYPHILIS IN RABBITS WITH ESPECIAL REFERENCE TO THE FACTOR OF INHERITANCE

The report is concerned with the occurrence of stigmata of syphilis in the progeny of syphilitic rabbits and the probable cause for such conditions in cases where no infection can be demonstrated. The history of a group of animals presenting these conditions is given and possible causes are discussed in the light of evidence derived from a study of these animals. In this instance, it appeared that the lesions suggesting syphilis were of functional rather than of infectious origin and that heredity was an important factor in determining their occurrence.     

THE DIRECT CULTIVATION OF TREPONEMA PALLIDUM PATHOGENIC FOR THE MONKEY

A method for the direct cultivation of Treponema pallidum from human syphilitic lesions, by the employment of a solid medium, has been described. By means of it, three of the four strains worked with were successfully cultivated. The several pure cultures agree in morphological and cultural characters, grow only in the presence of sterile tissue under anaerobic conditions, and do not produce putrefactive odors. The morphology is typical under optimum cultural conditions; it becomes atypical when the conditions are unfavorable. In cultures, Treponema pallidum multiplies by longitudinal division. The process is usually symmetrical but occasionally appears to be asymmetrical. Inoculation of the pure cultures into the skin of two species of lower monkeys was followed by the production of lesions resembling the primary syphilitic lesion occurring in man and those caused in the monkey by inoculation of spirochætæ-containing serum from human sources. During the course of the positive inoculation in the monkey, the blood develops the property of giving a positive Wassermann reaction. Thus the relation of Treponema pallidum to this reaction is supported, and the identity of the cultivated strains with the species found in human syphilitic lesions established.     

STUDIES BASED ON A MALIGNANT TUMOR OF THE RABBIT : I. THE SPONTANEOUS TUMOR AND ASSOCIATED ABNORMALITIES.

A malignant tumor which developed at the site of a primary syphilitic lesion in the scrotum of a rabbit, about 4 years after inoculation, and eventually led to the death of the animal, has formed the basis for an extensive series of investigations beginning with the study of the spontaneous tumor. The present report contains the clinical history of the animal from the time of inoculation to its death and the results of pathological examinations. The most important events recorded may be summarized as follows: 1. A mild but persistent syphilitic infection with an occasional relapse and the eventual development of chronic inflammatory lesions in the skin associated with atypical epithelial proliferations. 2. The occurrence, at about the same time, of extensive degenerative changes in the dermis accompanied by an atypical growth of hair follicles, with the production of diffuse and nodular areas of thickening and induration (scleroderma). 3. The development of a growth in the skin of the left scrotum which recurred after removal and spread diffusely over adjacent parts of the skin, and metastasized to the regional lymph nodes and to internal organs. 4. The transplantation of the growth to other rabbits by intratesticular inoculation and the successful propagation of the growth over a period of nearly 2 years (twenty generations). 5. The development of a cachexia and of pressure phenomena from metastases involving the cervical and lumbar regions of the spinal column which eventually led to the death of the animal. 6. The discovery, post mortem, of an extensive leucoplakia of the tongue and buccal mucosa, chronic inflammatory lesions in the esophagus with atypical epithelial proliferation, and a nodular growth in the left testicle differing in character from that in the scrotum. 7. The presence of extensive degenerative changes in the vascular system, degeneration of the parenchymatous organs, atrophy of the thymus and lymphoid system, with chronic lymphadenitis, atrophy, degeneration, and necrosis of the suprarenals, and atrophy and hyperplasia of the thyroid with chronic thyroiditis. The conclusion was reached that the growth in the scrotum represented a neoplasm of epithelial origin which was composed of cells allied to those found in the bulb and root sheath of the hair. No explanation was offered for the origin or unusual malignancy displayed by the tumor pending the introduction of experimental data. It was stated, however, that the evidence presented was sufficient to warrant the assumption that the factor of foremost importance in the development of the tumor was constitutional rather than local.     

SUPERINFECTION IN EXPERIMENTAL SYPHILIS FOLLOWING THE ADMINISTRATION OF SUBCURATIVE DOSES OF ARSPHENAMINE OR NEOARSPHENAMINE

Experiments were carried out on rabbits for the purpose of determining the effects of subcurative doses of arsphenamine and of neo-arsphenamine upon the resistance of infected animals to reinoculation with Treponema pallidum and hence the possibilities of the occurrence of a second infection in treated but uncured cases of infection. All the animals used were inoculated with the same virus, and the experimental tests were carried out when the first cycle of testicular reaction was nearing its height. The animals with the most marked testicular lesions were used for the basic experiment of treatment and reinoculation. The results of this experiment were controlled from four different standpoints: (1) the effect of the treatment employed upon the existing infection; (2) the immunity present at the time of treatment; (3) the virulence of the organisms used for reinoculation as compared with those causing the existing infection; (4) the comparative susceptibility of normal animals to the virus used for reinoculation. The results obtained showed (1) that the treatment employed was insufficient to cure any of the therapeutic controls; (2) that the infected controls were highly refractory to a second inoculation; (3) that the treated animals were highly susceptible to a second inoculation and although not cured of their original infection, reacted to the second inoculation with the formation of lesions indistinguishable from those of a first infection; (4) that in certain instances the treatment given had rendered infected animals more susceptible to infection than the normal controls.     

OBSERVATIONS ON THE BLOOD CYTOLOGY IN EXPERIMENTAL SYPHILIS : I. THE PERIOD OF DISEASE ACTIVITY

Weekly observations were made on the blood cytology of seven syphilitic and nine normal control rabbits. Each animal was examined seven times prior to and fifteen times after inoculation of the experimental group. Comparisons were made between the mean blood cell values obtained from all counts on the experimental and control groups in the preinoculation and postinoculation periods. The mean blood cell formula of the syphilitic group for the 3½ month period after inoculation was significantly different from the preinoculation mean values observed in the same group in the following respects: higher total white cell count, platelet count, neutrophil count, and monocyte count, and lower lymphocyte count. The mean blood cell formula of the syphilitic group for the 3½ month period after inoculation was significantly different from the mean blood cell formula of the normal control group in the same time interval in the following respects: higher total white cell count, platelet count, neutrophil and monocyte counts, and lower lymphocyte count. From these results it was concluded that during the period of disease activity, the blood cytology of rabbits infected with Tr. pallidum is characterized by an increase in the total white cell count, the platelet, neutrophil, and monocyte counts, and a decrease in the lymphocyte count from normal values. These changes were statistically significant.