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Recounts the author's adventures boating along various waters in Australia. Cruising along Burnett River to Bundaberg; Cost of in-and-out haulage; Adventures in Brisbane; Trip to Tin Can Bay; Travel to Mooloolaba.

The majority of investigators have interpreted the results of superinoculation experiments with Treponema pallidumas showing that one infection affords protection against another. The chief criterion for determining results has been the production of a characteristic lesion containing spirochetes, it being virtually assumed that if no lesion occurred no infection had taken place. When it is recalled that the lesion produced at the portal of entry in a first infection may be very slight or entirely absent1and that organisms may multiply in the body for months or even years without giving rise to any external manifestation of disease, it is obvious that such a standard of measurement is of more value as an index of the ability to produce a manifestation of disease than of infection, and that infection cannot be excluded upon this basis. It would appear, therefore, that before the results of superinoculation experiments can be made clear, the subject must be approached from a broader point of view and that evidence must be adduced which will enable one to see beyond the reaction at the site of inoculation.With this idea in view, a large series of superinoculation experiments was carried out on rabbits with five strains of Treponema pallidurnrepresenting organisms of a wide range of virulence for these animals. These strains included the highly virulent ones of Nichols and of Zinsser and Hopkins, isolated in 1912 and 1913, and three less virulent strains, isolated during the fall of 1919. In general, the animals were first inoculated in one or both testicles while the second inoculation was made intracutaneously on the sheath or at the base of one ear using equivalent doses of a testicular emulsion.

That a widespread dissemination of Treponema pallidummay be produced in the rabbit by local inoculation has been shown by the recovery of the organisms in isolated instances from the blood, lymphnodes or other organs as well as by the occasional occurrence of generalized lesions in infected animals. However, there is no evidence to show either the time or frequency with which this dissemination occurs or whether the organisms thus distributed over the body are capable of sustaining the infection in these animals.With these questions in mind, a series of experiments was undertaken, the object of which was to determine the frequency of invasion of the regional lymphatics and the general circulation following inoculation in the scrotum or testicles and how soon a self-sustaining generalized infection might be established.Time and Frequency of Invasion of Regional Lymphatics.- An examination was made of the inguinal lymphnodes in a series of 29 rabbits which had been inoculated by the introduction of a bit of infected tissue beneath the skin of the scrotum. The nodes were excised under ether anesthesia at intervals of from 61 days down to 48 hours after inoculation and the presence or absence of Treponema pallidurndetermined by dark field examination or by animal inoculation.The first group of nodes studied included those showing well marked enlargement and induration and these gave positive results in all cases. Nodes were then taken 5 days after inoculation and after the lapse of only 48 hours. Positive results were again obtained in all cases.

Two of the most striking features of the infection usually produced in rabbits by testicular or scrotal inoculations of well-adapted strains of Treponema pallidumare the marked reaction at the site of inoculation and the total absence of generalized lesions. In fact, these features of the reaction to infection are so conspicuous as to suggest a casual connection between the two, especially when it has been shown that the failure to produce generalized lesions can in no wise be attributed to the absence of a generalized infection or to an insusceptibility on the part of the animal's tissues to react to such organisms. Specifically, it appeared to us that in all probability, the failure to produce generalized lesions was due in a large measure to an inhibitory influence arising from the reaction at the primary focus of infection and that the reduction or suppression of this reaction might be sufficient in itself to permit the development of generalized lesions.In order to test this hypothesis, three types of experiments were carried out which were intended to compare the effects produced by unilateral and bilateral inoculations, the effects of castration and the effect of suppression of the primary lesions by the use of therapeutic agents. The castrations were done under ether anesthesia.Effects of Unilateral and Bilateral Inoculation and of Castration. -In the first series of experiments, there were 27 rabbits inoculated in one testicle and 20 inoculated in both testicles, giving a total of 47 rabbits. These were divided into two groups, one of which was castrated soon after the appearance of the primary lesion and the other held as controls. Both groups were kept under observation for a period of 4 months after inoculation.

Although it is now generally recognized that the time during which a syphilitic infection remains confined to the primary focus of entry is comparatively short, and that the effort to distinguish between a localized and generalized stage of infection is largely an arbitrary one, no one has shown just how rapidly the infecting organisms may spread after they have once gained entrance to the body or when a generalized infection may be said to have occurred. These are questions of obvious clinical importance and considerable light may be thrown on them by the sequence of events which follows local inoculations of Spirochaeta pallida in the rabbit.In a recent series of experiments, an attempt was made to obtain some data on these points by a systematic determination of the presence of spirochetes in the inguinal lymph nodes and the circulating blood of rabbits at various intervals after scrotal or testicular

A study of the circulating blood cells has been made on normal rabbits and on rabbits inoculated with various disease-producing agents including virus III. This filterable virus, indigenous to rabbits, causes well marked lesions of the testicle, skin, and scarified cornea when injected at these sites. In the experiments with this virus, the blood was studied at frequent intervals before and after inoculation by means of quantitative determinations of the red and white cells with standardized pipettes, hemoglobin estimations (New-comber haemoglobinometer), and differential white cell counts of the fresh blood with the supravital technic (vital neutral red).Three experiments have been carried out. Fresh testicular tissue showing a well developed virus III lesion was ground with sand and normal saline under aseptic conditions and 0.2 or 0.3 cc. of a thick emulsion was injected into one testicle or intracutaneously in the shaved skin of the side of the body. The first experiments comprised 5 normal rabbits which were inoculated intracutaneously and in one testicle; the second series of 5 normal rabbits were inoculated intracutaneously; in the third group, 8 rabbits which had previously been inoculated with a malignant tumor were injected intracutaneously.The outstanding feature of the observations made was a very marked increase in the number of circulating monocytes, as is shown in the accompanying graph (Fig. 1), which illustrates the findings in the first experiment. In the other series, the results were of the same order but were somewhat less marked, due presumably to the less pronounced reaction associated with the intracutaneous as contrasted with the intratesticular route of inoculation. The results, considered upon a group basis, are recorded as percentage variations from the mean values of 4 counts taken during the week preceding inoculation.

It is well known that many of the endocrine glands of normal animals undergo rhythmic changes in weight per unit of body weight which conform, in general, with seasonal conditions. Still, the cause of these changes is not clearly understood nor is it generally known that other organs and tissues such as the heart, the liver, the kidneys, the spleen, the thymus, the lymphoid tissues, and even the brain, undergo changes of a similar character.In November, 1921, we began a series of investigations which included among other things a study of the ratio of the weights of various organs and tissues to the body weight of normal rabbits and the limits of variation that might be encountered, with especial reference to the causes of such variations. The factors studied included age, breed, length of caging, time of killing (with reference to the regular system of feeding), and meteorological conditions. All of the animals used were males, and an effort was made to minimize the influence of dietary factors by maintaining a uniform system of feeding and a uniform diet consisting of hay, oats, and cabbage, which is the regular diet given all rabbits in these laboratories.The plan followed was to kill and examine two groups of rabbits each month selected from stocks that were being used for experimental work. All animals were well nourished and free from any external evidence of disease. During the first few months the groups were small and intentionally of a mixed character, but beginning with June, 1922, the monthly groups consisted of from ten to twenty rabbits.The animals were killed prior to the daily feeding; they were anesthetized with ether and bled from the inferior vena cava while the heart was still beating. The organs were removed, freed of all adventitious material, and weighed on suitable balances.

Since the tumor upon which this report is based was first transplanted in the spring of 1921,1we have been engaged in a study of the problem of animal resistance as related to the growth and malignancy of the tumor with especial reference to factors of constitutional resistance and conditions that might cause an increase or decrease in animal resistance.Several reports have been published dealing with some of the results of this series of investigations.2Among other things, it has been noted that although a good primary growth can be obtained in practically all rabbits by intratesticular inoculation, the ultimate malignancy of the tumor is subject to wide variations and that, from the beginning, there has been a striking tendency to the occurrence of periods of excessive malignancy during the spring and fall of each year. This focused our attention on the possible influence of meteorological conditions and led to a study of phenomena of resistance and of tumor growth from the point of view of meteorological influences. The results of these investigations contain many points of interest, but the present report will be limited to a consideration of sunlight.The method employed involved the inoculation of a group of 5 to 10 rabbits each month. Inoculations were made by injecting 0.2 to 0.3 cc. of a cell emulsion into one testicle. The animals were then kept under observation for a period of two months, at which time the surviving animals were killed. Records were kept covering the clinical course of the disease and all animals were subjected to a careful postmortem examination which included the weighing of organs, noting the number and distribution of metastases, and the extent and condition of the growth in all parts of the body. The data thus obtained were reduced to a form that would permit of a quantitative expression.

Experimental transmission of the spontaneous rabbit-pox discussed in the preceding communication1was attempted early in the course of the pandemic. Since the result of bacteriological examinations together with the clinical picture of the condition made it appear unlikely that we were dealing with any of the usual bacterial agents, the initial experiments were carried out with Berkefeld “V” filtrates of various organs and tissues from rabbits showing well marked symptoms of the disease. In other experiments, unfiltered suspensions were used. The organs employed included: testicle, liver, spleen, lung, popliteal lymph nodes, brain, spinal cord, blood, and skin. Injections were made into the testicles of rabbits procured from outside sources.The results of the first experiments were positive in that an orchitis and scrotal edema were pronounced within 48 hours, fever developed (105°-107°), the animals appeared ill, frequently a diarrhea was present, and death occurred in from 4 to 8 days. This condition has been produced successively from rabbit to rabbit by means of filtered material (usually testicle) and the agent is now in the fifteenth serial passage. Other routes of inoculation have also been successfully employed, namely, intracutaneous, subcutaneous, intravenous, intraperitoneal, intramuscular, intracerebral, and nasal and conjunctival instillation. By using small doses and certain routes of inoculation, it has been possible to reproduce all the clinical and pathological features of the spontaneous disease including the characteristic pock eruption of the skin and mucous membranes. In addition, complete recovery has occurred in these circumstances.The agent is active in tissue stored in 50% glycerol at ice box temperature for at least 94 days. Unfiltered material is much more potent than that filtered through a Berkefeld “V” candle but an “N” filtrate is also active.

Blood examinations were made on a number of syphilitic patients20who were divided into 2 groups. One group consisted of 58 patients who had received no treatment up to the time of the blood examination. Thirty-two were seen in the stage of an active primary infection, 18 had active secondary lesions, and 8 had signs and symptoms of tertiary disease. The second group consisted of 55 patients who had received varying amounts of specific treatment, ranging from less than one full course of arsphenamine and mercury to several such courses. In 20 of these, treatment was instituted during the primary stage of the disease, in 16 treatment was begun during the secondary stage, and in 19 during the tertiary stage.Since the patients were ambulatory and repeated counts could be obtained only with great difficulty, one complete blood examination was made on each individual. Each examination included a total red and white cell count made with standardized pipettes, a hemoglobin determination by the Newcomer method, a platelet count by the Ringer-heparin method of Casey,1, 2and a differential white cell count made with the supravital technique, 100 cells being counted on each of 2 smears. The blood findings in these 2 groups were then compared, and the mean and standard error of the mean was determined for each blood element. A difference was considered to be significant when the probability of its occurrence by chance was less than one in 100.In the treated group as compared with the untreated patients, the hemoglobin level and the absolute and relative numbers of lymphocytes were significantly higher, while the total white cells, the number of platelets, the absolute and relative numbers of neutrophils, and the absolute and relative numbers of monocytes were significantly lower.

Little information is available regarding the clinical reaction of the rabbit to cutaneous inoculation of dermo-vaccine virus except as regards the local reaction at the site of injection. Furthermore, factors which presumably might affect the response as, for example, age, have not generally been considered. Our interest in the matter arose from the results obtained in the vaccination of the rabbits of a large breeding colony. The experiments are still in progress but enough has been learned to show that the clinical reaction of the rabbit to vaccination is extremely variable and that these variations are associated with a number of factors which concern the host.Approximately 1800 rabbits were vaccinated in December, 1933, and January, 1934, with culture dermo-vaccine virus obtained through the kindness of Dr. T. M. Rivers. The injections were made intracutaneously with dilutions ranging from 1:50 to 1:40,000. Previous tests had shown that the virus was active in a titre of 1:100,000 to 1:1,000,000 injected intradermally. Certain outstanding results of the experiments may be briefly summarized as follows.A typical local reaction developed in the adult non-immune stock of both sexes but it was much more severe in bucks than in does, and more pronounced in resting than in pregnant and nursing does. Generalized manifestations consisting in particular of a cutaneous maculo-papular eruption in areas remote from the injection site, as for example, the ears, were not infrequent. A lymph adenitis was also observed and an orchitis in male animals developed in many instances. There were a few cases of pronounced illness and prostration but only 3 fatalities.The results were quite different in the younger stock, all of which were presumably susceptible. In the first place, a local reaction did not develop in a large proportion of these rabbits and the incidence of negative results was inversely proportional to age.

Experiments to determine whether the Chinese hamster is susceptible to inoculation with Treponema pallidumhave shown that organisms pathogenic for the rabbit may be recovered from certain tissues of this animal species. It would appear that there is dissemination of the organisms from the local focus of inoculation and presumably a multiplication of them occurs.Hamsters were injected in one testicle with a tissue (orchitis) emulsion rich in spirochetes obtained from rabbits which had been inoculated with either the Nichol's strain or with a strain (P III) isolated from a patient in this hospital in 1926. At varying periods, the hamsters were killed by ether anesthesia and different tissues, emulsified with sterile normal saline were injected intratesticularly in normal rabbits. The rabbits were under observations approximately 3 months. In the case of those in which a clinical orchitis was not detected together with darkfield demonstration of spirochetes, the inoculated testicle and the popliteal lymph nodes were injected in a second set of rabbits; in a few instances, this procedure was repeated in a third set of rabbits.The available results on the first generation of rabbit transfers may be summarized as follows: (1) In rabbits injected with the inoculated hamster testicle, 37, 64, and 138 days previously, a syphilitic orchitis developed in 2 to 3 weeks. (2) The inguinal lymph nodes of a hamster which was inoculated 64 days previously, induced a syphilitic orchitis in 2 rabbits in 7 and 9 weeks respectively; nodes from a hamster inoculated 138 days previously gave negative results in one rabbit. (3) Brain tissue of a hamster injected 138 days previously, induced a syphilitic orchitis in a rabbit in 43 days; negative results followed the injection of brain tissue of 2 hamsters injected 37 to 64 days previously.

The fact may be recorded that highly virulent strains of Treponema pallidumare capable of penetrating some portion of the genital mucosa of normal rabbits and setting up an infection without necessarily producing the first gross lesion at the portal of entry. This fact was recently determined in 9 rabbits and with two highly virulent strains of Treponema pallidum.The experimental method employed was as follows: The sheath of the animal was drawn forward to form a pouch into which was instilled 0.05 c.c. of a testicular emulsion rich in spirochetes. About 30 seconds were allowed for the emulsion to spread before releasing the sheath. Most of the fluid then ran out and between 0.04 and 0.05 c.c. could be recovered showing that only a thin film of the emulsion was retained. Infection was first indicated by enlargement and induration of the inguinal lymphnodes and later by the development of a general lymphadenitis with syphilitic lesions in other parts of the body.All animals thus far inoculated by this method have become infected. In some of them, enlargement and induration of the inguinal nodes was clearly recognizable within 24 hours after the application of the emulsion. Thus far (5 weeks) only one of the animals has developed a visible lesion on either the penis or the sheath, although several of them have characteristic lesions in the testicles and scrotum.The observations on these animals are not yet complete and the full significance of the experiments cannot be ascertained until the course of the infection has been followed much longer. Similar experiments with other mucous membranes are in progress.

Neoplasia as a sequel to syphilitic infection is not uncommon in man but has never been recorded in an experimental animal. Recently, we have observed an atypical growth arising from the scar of an old syphilitic lesion in the scrotum of a rabbit which may prove to be a neoplasm.The animal was inoculated in the scrotum, June 16, 1916. Small chancres developed and then underwent spontaneous regression. Several months later, there was a recurrence and the lesion in the left scrotum persisted for some time. In October, 1920, there was a slight diffuse infiltration of the left scrotum and a small nodule appeared at the site of the old chancre. Although it was known that the animal still harbored spirochetes,1none could be demonstrated by dark-field examination of material from the nodule and it was excised for histological examination. There was a prompt recurrence and with the growth of the second cutaneous lesion, the left inguinal glands became markedly enlarged and indurated. Again no spirochetes could be demonstrated and the lesion with one of the adjacent glands was excised under ether anesthesia. Histological examination of the cutaneous nodules and gland showed a growth which presented more the appearance of a neoplasm than of a syphilitic lesion. It was composed for the most part of atypical epithelioid cells undergoing active proliferation and exhibiting marked invasive tendencies.Meantime there was a second recurrence and extension of the skin lesion over the mid line at the pubis with enlargement and induration of the right inguinal nodes. A deterioration in the physical condition of the animal was then apparent and progressed very rapidly, culminating in emaciation, weakness, severe anemia, loss of sphincter control with some spasticity of the hind legs and the formation of trophic ulcers about the anus and sheath.

A study has been made of the cells of the circulating blood of normal rabbits and of rabbits inoculated with various disease-producing agents1, 2including a transplantable malignant neoplasm3believed to be of epithelial origin. The results concerning the monocytes in this condition are referred to in the present report.A variable number of blood counts were taken preceding inoculation and thereafter for 2 months, at which time the experiments were arbitrarily terminated by killing all surviving animals. For the most part, the blood was examined at weekly intervals; a differential white cell count with the supravital technic (vital neutral red) was made at each examination. Six experiments comprising 47 rabbits have been carried out from October, 1927, to March, 1929. In each experiment, a suspension of fresh tumor tissue in normal saline was injected in one testicle of young adult male animals. The course of the disease was followed clinically and the autopsy findings furnished further information concerning the extent and degree of the disease process.The blood observations have been analyzed with respect to the clinical and postmortem findings and in the present instance, are considered from a group standpoint. The following classification of animals has been employed: deaths, probable deaths, and recoveries. The first group includes examples of widespread metastatic involvement; the probable deaths comprise those rabbits in which the site and character of the growth found at autopsy 2 months after inoculation were such as to make it appear probable that death would ultimately have resulted from tumor; the recoveries include those animals in which healing of tumor had occurred and in addition, a few instances of slight residual tumor, the nature or location of which was considered as not constituting a probable cause of death.

The influence which one infection may have upon the manifestations of another has been investigated in a number of conditions in connection with a general study of the factors concerned in determining the course and outcome of disease processes. In the case of syphilis and vaccinia of the rabbit, the result of simultaneous inoculations of Tr. pallidumand vaccine virus has been studied. Other experiments have dealt with the syphilitic reaction in rabbits immune to vaccine virus, and conversely, with the vaccine reaction in rabbits infected with Tr. pallidum.The Nichol's strain of Tr. pallidumand the Noguchi strain of vaccine virus were used; groups of 5 or 10 male rabbits were employed for each series. The syphilitic tissue emulsion was injected in one testicle or intracutaneously on the sheath; the inoculation of vaccine virus was made on the shaved skin of the body by rubbing the infected tissue emulsion into scarified areas, and by intracutaneous injection. In other groups, the syphilitic and vaccine virus emulsions were both injected in the same testicle. Control series of rabbits were inoculated with each of these materials.The observation period varied from 3 to 5 months. An essential requirement of the work was the frequent examination of the rabbits in order that the syphilitic process in the several groups could be compared. The features of this infection which are especially important for such comparisons are illustrated by the following examples: the incubation period, character and duration of the primary and metastatic orchitis, the occurrence of scrota1 edema, the time of development of generalized lesions, their distribution, number and duration, and the initiation of latency, that is when all manifestations of the disease have healed.

During the last two years, our study of animal resistance has included investigations on the endocrine mechanism as one of the factors involved in the reaction of the host to disease processes.1,2,3Operative procedures of various types have been carried out on the thyroid, thymus, and suprarenal glands of rabbits, and the majority of animals have been inoculated with Treponema pallidumor a malignant tumor of the rabbit4either before or after operation. The rabbits so operated upon have been kept under observation from three to ten months, and at the conclusion of the experiments a complete autopsy was carried out in each instance. In this communication we wish to present a summary of the operative results upon the thyroid and thymus from the point of view of operative mortality, wound infection, and the incidence of residual nodules of gland tissue.Complete thyroidectomy has been performed in 103 instances with an operative mortality of 3.9 per cent (4 rabbits). These deaths occurred among our early operations and were attributed to over-anesthetization; in one instance there was an acute pulmonary emphysema. We have had no fatalities in the last 54 operations. The only case of wound infection occurred in the one animal in which local anesthesia was used and in which there was also an extensive mange. Up to the present time, 90 of the rabbits have been autopsied, and in four instances (4.4 per cent) tiny nodules of hyperplastic thyroid tissue have been found in close connection with a silk ligature.A partial removal of the thyroid has been carried out in 30 rabbits. In 24 instances one lobe and the isthmus were removed while in six the operation included the ligation of the blood supply to the remaining lobe. There has been one operative death, or 3.3 per cent, and no instance of wound infection.

In connection with a previous study of the susceptibility of the Chinese hamster (Cricetulus griseus)to syphilitic infection,1it was noted that normal rabbits developed strongly positive Wassermann reactions after being injected with hamster tissues in which the syphilitic virus could not be demonstrated by rigid biological methods. The question arose as to whether the tissues of the normal hamster, when injected into the rabbit, are capable of inducing Wassermann reactive bodies in the circulating blood. Consequently, further studies were made on rabbits injected with various tissues of normal hamsters. The following is a summary of the results obtained with injections of various tissues by different routes.Unless stated otherwise the hamster tissues used were emulsified in sterile normal saline shortly before being injected into the rabbit. Wassermann tests were made on the blood serum according to the Kolmer technique.2This method proved to be quite reliable in our hands. Among 71 normal rabbits tested there was only one false positive reaction in an animal which was in poor physical condition.1. Testis.Seventeen rabbits received 0.5–1.0 cc. of the emulsion intratesticularly, and all of these developed a positive Wassermann reaction. In one rabbit injected intraperitoneally the same positive result was obtained. Two other animals injected subcutaneously into the right flank, gave similar results. Two rabbits injected intravenously with the emulsion which had been filtered through sterile gauze, in doses of 0.3 and 0.5 cc, showed a weakly positive reaction in the blood.2. Brain.All 7 rabbits injected intratesticularly with the emulsion developed a strongly positive Wassermann reaction, while 2 other animals injected intravenously gave negative results.3. Whole blood(not treated with saline). Each of 5 intratesticularly injected rabbits developed a fairly strongly positive Wassermann reaction. In another animal, injected subcutaneously (0.2 cc.), the reaction was weakly positive.

During the course of an investigation of a spontaneous epidemic of rabbit-pox,1, 2observations were made on the blood picture of the experimental disease. Standardized pipettes and the supravital technique were employed in making the blood examinations. Striking quantitative changes were noted in two classes of cells. During the height of the disease there was a marked decrease in the number of lymphocytes and an enormous increase in the number of circulating monocytes.In a group of 12 animals systematically studied, the lymphocytes fell from a mean preinoculation level of 2473 or 35.1% of the total count to 847 or 7.5% on the third day following intratesticular inoculation. This was an actual decrease of 65.8% or a relative decrease of 78.6% from the preinoculation lymphocyte level. Simultaneously monocytes rose from a preinoculation value of 374 (5.4%) to 1534 (12.4%) on the third day following inoculation, an actual increase of 310%, or a relative increase of 185% from the mean preinoculation finding. The total white count rose from a mean preinoculation level of 6,971 to 12,530 on the third day. The extreme potency of the virus is evidenced by the fact that 5 of the 12 animals died on the third day after inoculation, and all were dead on the fifth day.Single observations were made on a large number of animals presenting a milder, more chronic form of the disease. Similar changes were observed. Lymphocyte values of less than 1000 per cm. and monocyte counts of more than 3000 were not uncommon. In relative per cent, the lymphocytes frequently composed less than 8% of the total count while monocytes sometimes rose to 40 and 50%.Attention has been called to the monocyte-lymphocyte ratio in tuberculosis3and syphilis.4