310 Action of the Genetic Material 



obviously to be used in protein synthesis (perhaps via RNA), to 

 which no specificity can be attached in these cases (see I 2 B b dd). 

 We refer further to the mass removal of RNA from chromosomes 

 without any further function (see I 2 B a). 



At this point a much-discussed question enters: Does the genie 

 material produce its action in a single determinative act, that is, by 

 extrusion of the specific active gene products into the cytoplasm, 

 followed by autonomous self-duplication which involves all active 

 substances like enzyme systems? Or is a continuous genie function 

 necessary for replacement of such substances? The former idea is 

 more or less that of the plasmagene, produced by interaction of 

 nuclear genes with specific cytoplasm. If general metabolic processes 

 are involved, which may also include morphogenesis of a kind, such 

 experiments as those of Hammerling (see III 2) clearly show that, 

 after a certain time, the processes cease in enucleated pieces and can 

 be restored by restoring the nucleus. However, it is not easy to draw 

 conclusions from such facts concerning embryonic determination 

 where the difficulty does not lie in the fact of determination but in 

 its spatial and temporal order. This indicates that the problems are 

 of a quantitative and kinetic type rather than of a qualitative type, 

 which in the end is forced to endow the gene products with genie 

 qualities; thus we come to a solution of the problem which is no 

 solution. Discussions of these problems from different points of view 

 are found in Brachet (1947, 1950a), Spiegelman (1948), Darlington 

 and Mather (1949), Wright (1945), Marshak (1948), and Mazia 

 ( 1952 ) . We believe that here the qualitative biochemical outlook will 

 turn out to be secondary to the facts and conclusions from physio- 

 logical genetics. 



Thus I should think that the extremely interesting facts just 

 described, which were brought to light by the most painstaking work, 

 will help one day in the understanding of the growth and synthesis of 

 proteins without shedding light upon the genically controlled proc- 

 esses. The introduction of the very doubtful plasmagene concept (see 

 II 2 E) can only obscure matters by simulating an explanation. I 

 conclude that the qualitative, biochemical study of development has 

 not yet touched the problem of genie action. Sonneborn (1951a) 

 recently expressed a similar view (though he was speaking of Protozoa 

 and yeasts as models of genie action) when he said, "It must be 

 realized that none of the models seems yet to touch the master 

 problem of the control of the pattern of cellular changes in time and 

 space during the course of development." Thus at the end of all this 



