228 



FINE-STRUCTURE OF PROTOPLASM 



II 



As the native nucleic acids have a much higher molecular weight, the 

 woof would not consist of short chains with four members but of 

 much longer chains. The heteropolar salt bonds between the acid 

 groups of the nucleic acid chains and the basic groups of the poly- 

 peptide chains would have to be considered as the junctions of this 

 network (Fig. 125 b). 



»t = =2-t 



Biti?-t4 





h) 



iMm 



d 



«') 



Fig. 125. Submicroscopic arrangement of nucleic acid (shaded); a) in the head of the 

 spermatozoon of Sepia (after Schmidt, 1937a); b-d in the chromonema: b) transversal 

 (after Wrinch, 1936), c) lengthwise (after Schmidt, 1937c, 1939b), d) scattered orienta- 

 tions (from Frey-Wyssling, 1943b, 1944a). 



This scheme is not supported by the optical properties. The arti- 

 ficial nucleic acid threads obtained by Schmidt (1957a) are optically 

 negative^ ; and since in the spinning the molecular chains are arranged 

 parallel to the axis, the polynucleic acid chains themselves must also 

 be optically negative. It follows from this that the molecules of the 

 nucleic acid chains in the sperm nuclei (Schmidt, see Fig. 125 a) run 

 parallel to the morphological axis of the sperm head. But the poly- 

 peptide frame of these nuclei also must be orientated in the same 

 direction. This means that the chain molecules of both nuclear com- 

 ponents show parallel alignment. 



The chromomere discs of the chromosomes of the saUvary glands 

 are optically negative (Schmidt, 1937c, 1959b). For the submicro- 



1 Threads of sodium thymonucleate show a reversal of their sign of double refraction 

 when strongly stretched (Wilkins, Gosling and Seeds, 195 i). 



