xii HORMONES AND HEREDITY 



the development of the body from the ovum is not 

 an influence at all but a direct conversion by cell- 

 division and differentiation of the ovum into the body. 



Delage argues that if the egg contains the sub- 

 stances characteristic of certain categories of cells of 

 the organism it ought to be affected at the same time 

 as those cells and by the same agents. He thinks 

 that the egg only contains the substances or the 

 arrangements characteristic of certain general 

 functions (nervous, muscular, perhaps glandular 

 of divers kinds) but without attribution to localised 

 organs. In his view there is no representation of 

 parts or of functions in the ovum, but a simple 

 qualitative conformity of constitution between the 

 egg and the categories of cells which in the body are 

 charged with the accomplishment of the principal 

 functions. Thus mutilations of organs formed of 

 tissues occurring also elsewhere in the body cannot 

 be hereditary, but if the organ affected contains the 

 whole of a certain kind of tissue such as liver, spleen, 

 kidney, then the blood undergoes a qualitative modi- 

 fication which reacts on the constitution of the egg. 



Suppose the internal secretion of a gland (e,g, 

 glucose for the liver, glycolytic ferment for the 

 pancreas) is the physiological excitant for the gland. 

 If the gland is removed in whole or in part the pro- 

 portion of its internal secretion in the blood will be 

 diminished. Then the gland, if the suppression is 

 partial, will undergo a new diminution of activity. 

 But in the egg the specific substance of the gland 

 will also be less stimulated, and in the next genera- 

 tion a diminution of the gland may result. Thus 

 Delage states Massin found that partial removal of 

 the liver in rabbits had an inherited effect. In the 

 case of excretory glands the contrary will be the case, 



