1 8 DEFENSIVE FERMENTS OF THE ANIMAL ORGANISM 



impossible to imagine that the gland secretions of the 

 two different glands, which bring about the full 

 development of secondary sexual characters which are 

 obviously present from the first, should remain only 

 on one side of the body. They must, in fact, be 

 carried by the blood to all the cells of the body. 

 Nevertheless, the secretions of the male gland pass 

 only to those cells which have "male' properties, 

 and vice versa, the secretions of the ovary affect only 

 the cells of the " female ' half of the body. 



Strong support for this view of a specific cell 

 structure is supplied by the numerous experiments 

 on transplantation. The surgeon nowadays tries, as 

 much as possible, to retain the full strength of the 

 functions of every organ, and, if some of the tissues 

 are missing, he seeks aid in substitutes. It is found 

 that only those tissues graft which are taken from the 

 same species, while still better results are obtained 

 by the use of parts of the same individual. Hetero- 

 plasty, i.e., the attempt to graft foreign tissues, has 

 never succeeded. A body requires cells in harmony 

 with itself. If they are in close relation, as is the 

 case in tissues of the same species even the indi- 

 vidual has its own type then it is very probable that 

 with time the newly grafted tissue will, by means of 

 reconstruction, assimilate itself with the other cells 

 of the same organ, and so eventually with the entire 



organism. 



