Scientific Proceedings. 



(139) 75 



his first series of tumor transplantations the author obtained well 

 growing tumors after injection of cystic tumor-fluid into rats. In 

 such cases one or very few cells must have given rise to the tumor 

 growth, and these tumors developed in a few cases quite rapidly. 

 Such an explanation is, therefore, improbable. Further, we would 

 have to consider the possibility that the means employed to de- 

 crease the virulence of tumor cells are favorable to the growth of 

 bacteria, and that they inhibit in this way the development of 

 tumors. It is certain that bacterial toxins frequently act un- 

 favorably upon the growth of tumors. Against this explanation, 

 however, the objections can be raised that tumors with experi- 

 mentally diminished virulence did not show any sign of putrefac- 

 tion, nor did they, after inoculation, cause a formation of abscesses, 

 occurrences which are frequent after transplantation of infected 

 material. 



It is, therefore, most likely that the cause of this decrease in 

 virulence is the result of the direct decrease of the vitality of the 

 tumor cells as expressed in their energy of growth. It is, however, 

 desirable to further analyze these facts in future experimental work 

 on tumors, especially as the character of such work necessarily limits 

 greatly the number of experiments a single observer can make. With 

 this restriction it may be stated that the observations here recorded 

 point to the conclusion that it is possible to cause an experimental 

 increase or decrease in the energy of tumor growth, that these 

 variations may be caused by a direct stimulating or depressing in- 

 fluence upon the tumor cells, and that such a stimulating effect 

 may be cumulative. 



36 (82). " Demonstration : Photographs and plumage -charts of 

 hybrid poultry," with remarks : CHARLES B. DAVENPORT. 



Dr. Davenport exhibited photographs and plumage-charts of 

 four hybrids between different races of poultry, and also of their 

 parents, and remarked on the nature of the inheritance illustrated 

 by each example. 



37 (83)- " Experimental cirrhosis of the liver": RICHARD 

 M. PEARCE. (Presented by EUGENE L. OPIE.) 



The experimental studies upon which this communication is 

 based were suggested by an investigation of the necrosis produced 



