No. 581] 



GERM CELLS AND SOMATIC CELLS 



21)3 



normal tissues, are not produced, while in the former cases 

 such products acting directly or indirectly are formed. 

 As an illustration of such a specific relationship hetween 

 body fluids and tissues, I cited the specifically adapted 

 effect which tissue coagulins exert on the constituents of 

 blood plasma. 9 



Now as the result of these differences in metabolism 

 induced through the differently constituted body fluids the 

 lymphocytes begin to invade the transplanted tissues, and 

 the invading connective tissue does not preserve, as it 

 does after auto-transplantation, its young and cellular 

 state, but produces fibrous bands which contract around 

 the parenchyma after homoiotransplantation, and thus 

 exert pressure. Both connective tissue and lymphocytes 

 destroy thus the homoiotransplanted tissue, while they 

 usually spare the autotransplanted tissue the metabolism 

 of which is normal. In the case of certain tissues, as, for 

 instance, kidney, however, even after autotransplantation 

 into the subcutaneous tissue the metabolism of the trans- 

 planted cells becomes abnormal under the abnormal con- 

 ditions under which they now live, and here the lympho- 

 cytes and connective tissue destroy, therefore, even the 

 autotransplanted tissue, although at a later date than the 

 homoiotransplanted kidney tissue. 



The fitness of a tissue in an individual determining its 

 power to live or to grow depends, therefore, on two factors : 

 (1) on the specific adaptation existing between tissues and 

 body fluids, and (2) on the way in which various sub- 

 stances are carried to the tissue. A perfect nutrition im- 

 plies the carrying of the food substances to the tissues in 

 the normal way through blood-vessels. It is probable that 

 on the intact relations between capillary endothelium and 

 parenchyma cells depends such a sifting of various food 

 substances and waste products as is best suited to the 

 normal metabolism of the cells. If, as in the case of the 



stances are produced notwithstanding the specific adapta- 

 tion existing in this case between tissue cells and body 



9 "Immunity and Adaptation," Biol. Bulletin, Vol. IX, 1905, p. 141. 



