THE LAW OF BIOGENESIS 85 



normally occur, even in confusing detail. What 

 causes this orderly sequence of changes in the de- 

 velopment of all living things is a question still 

 unanswered. 



All know that no form of life comes into exist- 

 ence except through the division of some pre- 

 existing life (Biogenesis). All know that these 

 same forms of life go out of existence either by 

 a division of one individual into two as in Proto- 

 zoa, Fig. 12, or by the disintegration of the unity 

 of action of the cells composing the complex 

 body, namely, by death. When one comes to ask 

 how living protoplasm came to behave as it does in 

 reproduction there is as yet no scientific answer. 



