

REPRODUCTION 101 



material." This he proposes to call mito- 

 kinetism, and his view as a vitalist himself 

 is that "the discovery of this new force leaves 

 the vitalistic problem just where it was. 



We are now in a position to pass from this 

 part of the question and to consider another Division 

 of no less interest. The first division of the ovum 

 fertilised ovum had as a result the production 

 of a two-celled creature. Each of these cells 

 again divides, so that if division were always 

 regular in its progression, which it is not, we 

 should have the two-celled stage followed by 

 one of four cells and that by others of eight, 

 sixteen, thirty-two, sixty-four and so on. Such 

 a progress of division does take place in some 

 cases, but in others differences, as to which 

 nothing can here be said, are exhibited. But 

 whatever may be the sequence of division the 

 result is the formation of a creature which from 

 one cell has developed into a multicellular 

 organisation. It is obvious that this multi- 

 cellular organism might consist of identical 

 cells or of cells differentiated from one another 

 in groups so as to form different organs. Such 

 is the condition which is met with in all the 

 higher animals where, as, for example, in man, 

 differentiation is carried to a very great dis- 

 tance. Yet even in man the cells of the brain, 

 of the liver, of bone, muscle and skin, so 



