18 Nature of the Genetic Material 



and separation of the contents of the two fields by simple fission of 

 the amorphic part of the chromosome. In such a scheme the chromo- 

 some would split and not split, it would keep its morphological indi- 

 viduality and nevertheless disintegrate, it would re-create (self-dupli- 

 cation) but also divide (growth and fission), and it would lose and 

 reconstruct its intimate structure while remaining a unit. Up to this 

 point it does not make any difference what ideas we have about the 

 actual structure of the genie material. The theory of gene molecules 

 and the more modern ideas dispensing with corpuscular genes fit 

 equally well into the picture at the level of our present discussion. On 

 the contrary, it is possible that the genie material never has a micellar 

 structure but remains always an immense single-chain molecule, con- 

 nected somehow with the rest of the chromosomal material of which 

 it strips itself when dividing and afterward reassembling the whole. 

 Biochemically, this is the simpler assumption but otherwise the less 

 probable one. It is of course the old idea of the gene string, the 

 genonema of Koltzoff (see 1928, 1939). 



GENIC AND NON-GENIC PARTS 

 OF THE CHROMOSOME 



Thus far we have dealt only in a general way with genie and non- 

 genic parts of the chromosome in relation to chromosome division. 

 The next basic problem is to find out whether these two elements can 

 be distinguished morphologically, chemically, or by genetical experi- 

 ment. 



A. CONCLUSIONS FROM MORPHOLOGY 



It seems at once obvious that in this connection the centromere, 

 the nucleolus, the ground substance, or kalymma, and, where found, 



