2o6 Plant Genetics 



from generation to generation in the orderly manner 

 that the Mendelian data indicate, can we conceive of 

 their being located in the cytoplasm? Enzymes dif- 

 fuse rather readily through the cytoplasm; but if each 

 determiner were represented by an enzjone, what a 

 chaotic mixture this cytoplasm would be, with the 

 numerous determiner-enzymes intermingling, interact- 

 ing, and probably losing their specificity. This is not 

 the orderly picture required to account for the orderly 

 MendeUan results actually obtained. 



If, however, we conceive of these determiner- 

 enzymes inclosed in a linear arrangement along the 

 chromosomes we can paint a much more orderly picture. 

 The chromosome itself is not an active substance chemi- 

 cally; it is merely a framework, an "apartment house" 

 for determiner-enzymes, having, however, the power of 

 reproduction. Each determiner-enzyme is contained 

 (and "nourished") within its own compartment. When 

 the chromosome reproduces, each determiner-enzyme 

 reproduces within the chromosome and is passed on, at 

 all times, however, being well bound in by the walls of its 

 compartment and thus kept from reacting in the cyto- 

 plasmic medium which surrounds the chromosomes. 

 Sooner or later, as the automatic and inevitable result 

 of a natural series of physiological changes that has 

 taken place in the cell dynasty of the individual plant, 

 certain physiological conditions appear in the cytoplasm 

 which bring about the '"release" of certain of these 

 determiner-enzymes, which then react in the cytoplasm 

 to produce the specific plant characters of which they 

 are the determiners. If all these determiner-enzymes 

 had been released at once, or if they had never been con- 



