Tumor Inoculation 



473 



Two years ago, we reported the occurrence of a malignant 

 tumor in the scrotum of a rabbit infected with Treponema 

 pallidum? Since that time, a careful study has been made of 

 the conditions presented by this animal 6 and a long series of in- 

 vestigations based upon the behavior of transplanted tumors de- 

 rived from this stock has been carried out which have shown 

 that there is an essential connection between the growth of trans- 

 planted tumors and certain members of the endocrine system on 

 the one hand, and the mechanism of animal defense on the other. 



In the animal with the spontaneous tumor, there was a notable 

 tendency to atypical epithelial proliferation in many parts of the 

 body associated with a deficiency in the reaction of the sur- 

 rounding connective tissues and a widespread tendency to de- 

 generation. There were also very striking alterations in such 

 organs as the thyroid, the thymus, the suprarenals and the 

 lymphoid tissues, which might have been regarded as part of a 

 general organic deterioration attributable to one or both of the 

 diseases present. From our knowledge of the biology of 

 syphilitic infections and from what is known as to the influence 

 of this system of organs on animal economy, however, we were 

 led to suspect that the changes present might not be entirely 

 incidental. This suspicion was strengthened when it was found 

 that inoculation of other animals gave rise to decided alterations 

 in a number of the organs of internal secretion as well as in 

 the lymphoid tissues. With a view to determining whether these 

 changes were consequences of disease or possessed a functional 

 significance in tumor-bearing animals, especial attention was 

 given to the alterations that occurred in this system of organs. 



EXPERIMENTAL 



Since the fall of 1921, the thyroid, the parathyroids, the 

 suprarenals, the hypophysis, the pineal, and the thymus of all 

 animals inoculated with this tumor have been studied grossly 

 and histologically, including determinations of weight per unit 

 of body weight. As a means of control, like observations were 

 made upon normal rabbits derived from the same stocks and 



5 Brown, W. H., and Pearce, L., Proc. Soc. Biol, and Exper. Med., 

 1921, xviii, 201. 



G Brown, W. H., and Pearce, L., J. Exper. Med., 1923, xxxvii, 601. 



