Chapter 10 



Is It Possible by Experimental Means to Change 



Organismal Differentials? 



Individuality in the sense in which this term is used in our daily life 

 is considered essentially as a fixed condition, and the criteria of individ- 

 uality most commonly used are certain structural and functional peculiari- 

 ties of those parts of an organism which are readily perceived through the 

 sense organs. Yet, this mosaic individuality is not as constant as it might 

 appear ; to some extent, the parts constituting it may be under environmental 

 control and therefore modifiable. However, we have recognized that there is 

 hidden beneath these criteria something representative of individuality which 

 under ordinary circumstances is constant, namely, the organismal differen- 

 tials, and the individuality differentials in particular. But we have also, on 

 various occasions, referred to experimental findings which might suggest a 

 certain modifiability of the organismal differentials, and which are, there- 

 fore, apparently opposed to the fixity which is characteristic of this type of 

 individuality. Yet an analysis of these data showed that there was no reason 

 for assuming that an actual change in the organismal differentials had taken 

 place; on the other hand modifications in the reactions against organismal 

 differentials were noted in many instances. 



This interpretation accords with the genetic origin of the organismal dif- 

 ferentials; they are determined by the genes of the fertilized ovum acting in 

 association with the cytoplasm of the growing and of the adult tissues. While 

 the type of the organismal differentials produced by or inherent in the 

 tissues of a certain individual or species is constant, except if germinal 

 mutations should alter the genetic constitution, the amount of these differ- 

 entials produced might vary under different conditions. Furthermore, the 

 sensitiveness of a tissue against homoio- or heterotoxins and against strange 

 host cells might undergo some modifications under various conditions. 

 Changes in the growth momentum of tissues, or specific adaptations of a 

 tissue to strange substances may occur and changes in the intensity of 

 reactions against strange organismal differentials may be observed under 

 certain conditions. After we have now considered all the principal data 

 concerning the interaction of blood and tissues and their various constituents, 

 those belonging to the same individual, as well as homoiogenous and heterog- 

 enous ones, it might be of interest, to consider connectedly the main observa- 

 tions which may have a bearing on the problem of the modifiability of organis- 

 mal differentials. 



1. We have observed that after homoiogenous transplantation of cartilage 

 of guinea pig or rat, the lymphocytic reaction, which may be quite pronounced 

 in the first three weeks following transplantation, instead of becoming 



580 



