Introduction 247 



consider the physiological geneticist to be a kind of intruder. Spemann 

 once attacked Haecker rather violently when the latter proposed the 

 term "phenogenetics" for work on genie action in development, and 

 insisted that this is embryology and nothing but embryology. Only 

 recently De Beer (1951) has taken up this cudgel, when he wrote, 

 "He [the geneticist] need not have worried about the production of 

 the effects, for that lay in the province of the experimental embryolo- 

 gist, and not his." In spite of such isolationism or possessiveness, the 

 geneticist will continue to worry about the problem of genetic action 

 and take the risk of climbing over the fence erected by some jealous 

 embryologists, who, while claiming the kingdom for themselves, do 

 not set out to till its soil. 



The special division of physiological genetics which deals with 

 genically controlled, definite biochemical syntheses has been termed 

 by Beadle "biochemical genetics." This term might raise false hopes 

 if it is not realized that it is used for one selected aspect of genetics 

 only, the genetic interference with the synthesis of nutritional re- 

 quirements of the organism and definable end products of metabolism 

 and other deposits, though it is acknowledged that a distant ideal is 

 the resolution of all genetic actions into their biochemical components. 

 At this time biochemical genetics would become identical with 

 genetics. 



Altogether, physiological genetics in the wider sense covers: (1) 

 the biochemical nature of the genie material; (2) its primary action 

 at the site of its location in the chromosome; ( 3 ) its action within the 

 nucleus; (4) its action upon the cytoplasm of the individual cell; and 

 (5) its supracellular action in controlling growth, differentiation, de- 

 velopment, and biochemical specificity of the organism. It comprises 

 also the special part of no. 4, which has been termed biochemical 

 genetics. 



Though complicated in detail, in a general way genie action 

 should follow a relatively simple pattern. I have repeatedly empha- 

 sized (e.g., 1920a, 1927, 1938a) that one of the marvels of living nature 

 is the exactness of timing and type of developmental processes. Any- 

 body who has watched thousands of sea urchin eggs developing 

 simultaneously one like the other must have been impressed with this 

 fact. This means to me that the most complicated developmental 

 processes must, in the end, be controlled, steered, by rather simple 

 causative agents. 



I have tried to work out what I just called a simple pattern 

 ( Goldschmidt, 1920a, 1927), which in its general form seems to have 



