390 WILLIAM H. COLE 



of the ten grafts made were alike in this respect. Therefore, the 

 conclusions drawn from the results of the other kinds of grafts 

 are valid also when skin from the belly is transplanted. 



The final series of autotransplants consisted of belly skin 

 grafted on to the tail. There were six of these grafts. It is not 

 necessary to describe their histories in detail, because in general 

 they were similar to those in the other series. The conditions of 

 wrinkling were not quite so pronounced as when back skin was 

 used. The important observation is that all of them preserved 

 their individuality. 



It has been shown by reciprocal transplantation that in three 

 regions of the tadpole's body a specificity exists. However such 

 a condition may be explained, whether simply by postulating on 

 good evidence from other sources, a specific protein in the proto- 

 plasm, or mystically by assuming the presence of some vital force 

 the fact remains that wherever skin may be successfully trans- 

 planted on the same animal, the specificity and not the environ- 

 ment determines its behavior. The specific protein, however, 

 is not different enough from that in another region to set up a 

 violent reaction when the two are brought into contact. If such 

 a reaction did occur, the grafts would be destroyed, owing to the 

 excess of host substance over graft substance. 



3. Homoiotransplants 



Homoiotransplants of integument from the back or belly ex- 

 hibited striking differences when compared to the same kind of 

 autotransplants. There were two constant features of the eleven 

 homoiotransplants. The first was a vascular congestion, which 

 appeared as a network of blood vessels and spaces, making the 

 graft conspicuously red. Through the microscope the circula- 

 tion of the blood in this network could be observed. Histological 

 preparations showed accumulations of blood ceUs massed not only 

 beneath the dermis, but also between the dermis and the epider- 

 mis. The time when congestion appeared varied from twenty- 

 four hours after the operation to four days. Its duration aver- 

 aged three days. Both its appearance and disappearance 

 required twelve hours each. Following the disappearance of 



