134 HOW ANIMALS DEVELOP 



be built up wholly by digging downwards to the sim- 

 pler foundations. We must also build up, on whatever 

 foundations are available at the time, some system of 

 explanation for the more complex phenomena which 

 we see around us. We cannot claim to understand how 

 animals develop until we can explain how the various 

 individual processes of protein synthesis are integrated 

 with one another, and how the animal as a whole 

 comes to have a pattern and structure. Perhaps these 

 two problems are related. At any rate, we have to re- 

 member that they still face us with a lot of very diffi- 

 cult and fascinating questions. We know something 

 about how animals develop, but though our knowl- 

 edge is increasing all the time, we shall never know it 

 all. But then if we did know all about everything how 

 boring life would be. 



