Chromosomes and Genes 113 



The theories mentioned looked for subunits within the gene, 

 which still remained intact as a unit, though composite. But theories 

 of the opposite type also cropped up which, though still accepting the 

 corpuscular gene, did not consider it autonomous but tried to integrate 

 it into a larger functional whole. It was repeatedly assumed in a 

 rather vague way that the chromosome itself is one large molecule; 

 and the genes, side chains of it (e.g.. Castle, Renner, Correns). The 

 most detailed elaboration is that of KoltzofiF ( 1928, 1939 ) . He considers 

 the genie part of the chromosome to be a long protein molecule or a 

 bundle of such (the genonema). To these are attached radicals in a 

 definite position, and these are the genes, in which atomic change 

 represents a mutation. Complicated molecules like agglutinins are also 

 supposed to represent such genie radicals and these radicals reproduce 

 their like directly for use in the cell. Somewhat comparable ideas 

 were proposed by the chemist Wrinch (1936). She calls the chro- 

 mosome a molecular aggregate composed of chain molecules placed 

 end to end and held together by the links with nucleic acid mole- 

 cules. The gene then becomes a group of molecules between the 

 natural breakage points, that is, the bonds between the diflFerent mole- 

 cules in the chain. These and similar ideas (including some of my 

 own, 1930, 1932a) have this in common: they try to consider the gene 

 (which is still acknowledged as a unit) as a non-autonomous integral 

 part of a whole, thus leaving room for genie actions on a higher level 

 of integration. 



These precursor ideas indicated a desire to break with the classic 

 concept of the corpuscular and autonomous gene. Further progress 

 was, however, not possible until the analysis of the salivary gland 

 chromosomes in Drosophila brought to our attention the importance 

 of chromosomal rearrangements after breaks, together with the 

 phenomenon of position effect. Though an increasing number of 

 prominent geneticists face this situation in one way or another, and 

 have expressed themselves in concurrence with my conclusions more 

 or less cautiously, there are many who still cannot decide whether to 

 discard the classic theory of the autonomous gene. They prefer to look 

 for interpretations of the critical and unfavorable facts in terms of a 

 somewhat liberalized theory of the classic gene, which is acknowledged 

 to be in a critical condition, but with some vague hope of ultimate 

 salvage. 



We hear the argument that the classic theory has done so much 

 for genetics and explained so many facts that there is no reason to 

 abandon it. I have repeatedly answered this argument with the use 



