476 



Scientific Proceedings (132) 



during the 2 years that the tumor has been under investigation, 

 it has shown distinct seasonal variations in malignancy which 

 have followed a definite order. During the summer, the disease 

 has been more benign than in winter while each spring and fall 

 there has been a marked increase in malignancy as determined 

 by such criteria as the rate of growth of primary tumors, the 

 incidence and distribution of metastases, the proportion of cases 

 of fulminating malignancy and the mortality of inoculated 

 animals. 



These variations in malignancy, or in animal resistance, coin- 

 cided with the existence of a given state of equilibrium or the 

 occurrence of readjustments of endocrine balance as shown by 

 the weights of these organs in control animals. But, the periods 

 of greatest malignancy occurred at the time of readjustment 

 from winter to summer or from summer to winter conditions, 

 that is, at periods of unstable equilibrium. 



From these observations, the general conclusion was reached 

 that the malignancy displayed by this tumor was largely a func- 

 tion of animal economy and that the resistance of the animal 

 to the growth of the tumor was conditioned upon the activity 

 of those organs ordinarily concerned in the regulation of growth 

 and maturity. 



236 (2196) 



Animal resistance and the endocrine system of the rabbit in 

 experimental syphilis. 



By WADE H. BROWN and LOUISE PEARCE. 



[From the Laboratories of the Rockefeller Institute for Medical 

 Research, New York.] 



In the course of the work that has been carried out in this 

 laboratory during the past 8 years, it has become more and more 

 apparent that of the several factors concerned in determining 

 the general course and severity of syphilitic infections, the 

 spirochete is of minor importance as compared with a num- 

 ber of other influences, especially the factor of animal resistance. 



