Genie and Non-genic Parts of the Chromosome 35 



normal cells, but more work is needed to clarify this point. Histones 

 are altered or lost during sperm formation in some animals, and 

 residual protein varies from tissue to tissue in the same organism. 

 Other protein fractions have not been studied in more than a few 

 tissues. It is quite possible that one of these may also show a quanti- 

 tative constancy." Swift's words "carrier of genetic specificity" are 

 not identical with "genie material," though I think that he meant 

 to say "are the genie material." We shall see that it is quite possible 

 (even probable) that DNA has much to do with the specificity of 

 the genie material without being it. 



bb. Information derived from the structure 

 of the nucleic acid molecule 



While the importance of nucleic acid, both in quality and quan- 

 tity, for the function of the chromosome cannot be denied, the 

 geneticist cannot help feeling that this does not necessarily mean that 

 DNA is the genetic material. It might mean that it is a necessary 

 chemical cog in the structural stability of the chromosome or in the 

 self-duplication of the genie material and the entire chromosome, 

 and (or) as an energy producer for the actions in the chromosome. 

 Actually, all these views have been derived from the chemistry of 

 DNA, though the most recent developments favor or seem to favor 

 the genie nature of DNA. In the main the following formula or a 

 similar one had been accepted until recently. The molecule is a 

 straight chain formed by the polymerization of nucleotides each of 

 which consists of a purine or pyrimidine base and the phosphate of 

 the desoxyribose sugar. There are four different bases in definite 

 proportions, adenine, thymine, guanine, and cytosine, which seem 

 to be attached platelike at a right angle. We shall consider first some 

 consequences of these older molecular formulae. 



Much has been made of the fact that Astbury's (1939) X-ray 

 analysis revealed that these flat rings of the bases are piled on each 

 other at a distance of 3.4 A from one to the next, because this is 

 also about the distance between the amino acid residues in a pro- 

 tein chain molecule (protamine), to which the nucleic acid is pre- 

 sumably joined in the chromosome, either always, or only, before 

 reproduction, as discussed in the chapter on biochemistry of the 

 chromosome. An important property of the molecule is the unusual 

 viscosity in solutions. This is explained by the assumption that the 

 molecule is a stiff rod and that in solutions these rods stick together 

 in a network, perhaps via hydrogen bonds. It is assumed that under 



