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Scientific Proceedings (132) 



function of animal resistance as indicated by the course of the 

 disease and the conditions existing at the time the animal was 

 killed. 



The results obtained from these examinations were controlled 

 by similar observations made on a larger series (182) of normal 

 rabbits derived from the same sources and comparable as to age, 

 sex, breeds, length of caging, diet, and time and mode of killing. 

 As a further means of control, similar observations were car- 

 ried out on 51 rabbits with various forms and degrees of acute 

 and chronic infections of spontaneous origin and by a comparison 

 with effects produced by tumor inoculation and by inoculating 

 first with Treponema pallidum and then with the tumor or vice 

 versa. 



RESULTS 



The results of these experiments cannot be reported in detail 

 but they show conclusively that, apart from any localized lesions 

 which might be attributed to syphilis, there were definite changes 

 in the weights of such organs as the thyroid, the parathyroids, 

 the suprarenals, the hypophysis and the thymus, as well as in 

 the liver, the spleen, and the lymphoid tissues in general. The 

 majority of these organs showed distinct changes in appearance 

 and structure which were especially noticeable in the thyroid, 

 the parathyroids, and the thymus. Moreover, the status of the 

 organs at one stage of the infection differed from that at an- 

 other and, in general, the direction and magnitude of the change 

 that occurred was proportional to and parallel with the resist- 

 ance displayed by different groups of animals. Finally, it was 

 found that the changes which took place as the disease was 

 brought under control and immunity was established were of a 

 more or less permanent character. In other words, such organs 

 as the thyroid, the parathyroids, the suprarenals, and the thy- 

 mus, did not revert to their normal size and appearance but main- 

 tained a condition suggestive of a higher plane of functional 

 activity and of a change in the general relationship of one organ 

 to another. 



In severe infections, some of these glands showed unmistak- 

 able evidences of injury. This was most noticeable in the case 

 of the thyroid and the parathyroids but on the whole it appeared 

 that the changes were related to alterations in functional activity 

 which had to do with the development and maintenance of the 

 resistance to infection. 



