Xo. (»;!()] 



FAMILY RELATIONSHIP 



53 



substances is interfered with, and that thus cirrhotic 

 processes may be produced in various parenchymatous 

 organs. The usual assumption is that all these fibrous 

 changes are the result of an actual destruction of the epi- 

 thelium, that they are therefore due to regeneration in 

 the more restricted sense of the term. It is probable that 

 both these processes may occur in different cases. 



As we have shown, various tissues, but particularly the 

 lymphocytes, are able to distinguish not only between 

 tissues belonging to the same and other individuals of 

 the same species, but even to recognize the difference in 

 degree of relationship. They behave in a graded man- 

 ner towards their own tissues, the tissues of a brother, 

 mother, the tissues of a not related individual of the same 

 species and the tissues of an individual of a . different 

 species. These reactions must be in response to specific 

 substances given off by these tissues, the autosubstances, 

 the syngenesio-, homoio- and heterotoxins. Whether 

 these substances are identical with the individuality- 

 differentials residing in the tissues or whether they are 

 due to an interaction between the individuality-differ- 

 entials residing in the tissues and adapted substances in 

 the body fluids can not be decided definitely at present; 

 however, the latter assumption seems to be more prob- 

 able. These responses represent to our knowledge the 

 finest biochemical reactions which are known at the 

 present time and surpass even the immune reactions 

 which permit us to distinguish only between different 

 species and in a few cases only between individuals of the 

 same species. 3 



These reactions we may hope will contribute to an 

 understanding of the behavior and the functions of 

 tissues in general as distinct from the specific functions 



