50 THE BIOLOGICAL BASIS OF INDIVIDUALITY 



In the development of placentomata in the homoiogenous uterus of the 

 guinea pig we see another example of a direct injurious action of the homoio- 

 toxins present in the circulating bodyfluids, which damaged the mucosa of the 

 uterine transplant to such an extent that the formation of placentomata was 

 either prevented or much reduced under conditions in which normally the 

 sensitizing hormones would have made these growth processes possible. There 

 was, then, a struggle between the sensitizing hormones and the homoio- 

 toxins ; only in a few instances was the hormone action, in conjunction with 

 the mechanical stimulation due to the trauma, able to overcome the injurious 

 effect of the homoiotoxins. The lymphocytic infiltration was quantitatively so 

 weak that the reaction on the part of the host cells could not be held responsi- 

 ble for these growth-depressing effects. 



10. Transplantation of autogenous and homoiogenous kidney tissue. The 

 process of transplantation initiates tissue reactions in the host and 

 changes in the transplant. These may be due to general factors common to 

 autogenous and homoiogenous tissue; in addition, there are the specific re- 

 actions due to the varying degrees of incompatibility of the individuality 

 differentials of host and transplant. These differences in individuality differ- 

 entials activate the formerly quiescent host tissues in accordance with the in- 

 herited, constitutional characteristics of the latter. Furthermore, by comparing 

 the reactions in tissues transplanted into different locations, the general injury 

 to the tissues is found to vary in degree; in a particularly unfavorable situa- 

 tion, with increasing injury to the transplant, the general, less specific reac- 

 tions of various tissues which are caused by the injury, may dominate over 

 the more specific reactions which are induced by incompatibility between the 

 individuality differentials of host and transplant. It is in order to analyze 

 still further these characteristics of tissues that we shall record the principal 

 observations as to the differences between autogenous and homoiogenous 

 transplants of kidney tissue in the guinea pig. Greater damage is suffered by 

 these grafts, for instance, after transfer into pockets in the ear of guinea 

 pig than into pockets in the subcutaneous tissues of the abdominal wall or of 

 the dorsum. This is true of both autogenous and homoiogenous tissue and both 

 may die after some time, although the latter is earlier destroyed; also, the 

 specific differences between these two types of transplantation are less evident 

 in ear transplants than in those in the subcutaneous tissue of the anterior or 

 posterior wall of the abdomen. Likewise, homoiotransplants of uterine tissue 

 are destroyed more rapidly in the ear than in the abdominal wall. 



After transplantation into the ear of pieces of kidney, destruction of 

 homoiogenous tissue was complete after 21 days, while the autogenous tissue, 

 although injured by the ingrowing connective tissue, was not yet quite de- 

 stroyed at 38 days. Transplanted into the subcutaneous tissue of the abdominal 

 wall, both autogenous and homoiogenous kidney tissue was preserved for at 

 least 30 days, and it probably remained alive for a still longer period. These 

 differences were presumably due to the greater pressure exerted on the grafted 

 tissue in the ear and, perhaps, also to a less satisfactory blood vessel supply in 

 this region. The same factors caused also a much more marked lymphocytic 



