TRANSPLANTATION AND INDIVIDUALITY. 159 



unlike an inert foreign body. Correspondingly the amount of 

 fibrous tissue formed increases and the extent of vascularization 

 decreases in the direction from atitotransplant to heterotransplant. 

 The ability of the transplanted parenchyma to maintain a domi- 

 nance over the stroma, to keep the fibroblasts intact, and if pos- 

 sible in a myxoid condition and to cause the absorption of the 

 connective tissue stroma decreases in the direction from auto to 

 heterotransplant. Similar is the curve which represents the 

 stimulating power of the parenchyma on the vesselgrovvth. It 

 needs further investigation to determine how far the vascular re- 

 action is a primary phenomenon and how far the connective tissue 

 reaction depends upon it. The lymphocytic reaction on the other 

 hand reaches a maximum in the homoiotransplant and decreases 

 again in the heterotransplant. 



THEORETICAL CONSIDERATIONS. CONTACT SUBSTANCES, AUTO- 

 SUBSTANCES AND TOXINS. 



- 



Our results are best understandable, if we assume that the 

 cells in their metabolism give off a series of substances which 

 regulate the relation with certain other kinds of cells, and in par- 

 ticular the relation of parenchyma (epithelial, glandular, special 

 kinds of connective tissue cells and unstriated muscle) to the 

 surrounding connective tissue, blood and lymph vessels and 

 lymphocytes. 



We must conclude that the cells living under what we might 

 call " autocondition," give off another substance or another set of 

 substances from those living under " syngenesio," "homoio," 

 "hetero" conditions. We have found a graded injuriousness of 

 the latter kind of substances for the cells of the surrounding 

 tissues. They stimulate the surrounding tissues to reactions 

 which are pathological and which in the end lead to the destruc- 

 tion of the cells which produce these substances and call forth 

 these reactions. We have therefore called these substances " syn- 

 genesio," " homoio," " hetero " toxins. Conversely we may des- 

 ignate those substances which are given off by the normally func- 

 tioning cells under " auto " surroundings as " auto " substances. 

 They regulate the action of connective tissue cells, vessels and 



