2 THE BIOLOGICAL PROBLEM OF TO-DA Y 



ment. All they saw was the embryo becoming 

 adult, the bud growing out into a blossom, as the 

 result of a process in which nutrition transformed 

 smaller to greater parts. And so they regarded 

 development as a simple process of growth result- 

 ing from nutrition. Their mental picture of the 

 germ or beginning of an organism was an exceed- 



o o o o 



ingly reduced image of the organism, an image 

 requiring for its development nothing but nutrition 

 and growth. That the material eye failed to 

 recognise the miniature they attributed to the 

 imperfection of our senses, and to the extreme 

 minuteness and resulting opacity of the object. 



That it might satisfy our human craving for 

 final causes, the theory of preformation had to be 

 accompanied by a corresponding explanation of the 

 origin of the miniatures. Biologists had already 

 abandoned the error of such spontaneous generation 

 as the origin of flies from decaying meat, and, in 

 its place, had accepted the doctrine of the con- 

 tinuity of life, formulating it in the phrase, Omne 

 vivum e vivo (Each life from a life), and in the 

 similar phrase, Omne vivum ex ovo (Each life from 

 an egg). One creature issued from another, within 

 which it had lain as a germ, and the series was 

 continuous. Thus, the theory of preformation gave 

 rise to the conception that living things were a 

 series of cases or wrappings, germ folded within 

 germ. The origin of life was relegated to the 

 beginning, at the creation of the world : it became 

 the work of a supernatural Creator, who, when He 

 formed the first creatures, formed with them, and 



