BIOMOLECULAR ASPECTS OF SPERMATOZOAN MOTILITY 207 



The general effect of pH and electrolytes upon the precipitates 

 seemed to depend on some disturbance of the internal molecular 

 relationships, with the result that the gel specimens became unstable 

 and filamentous under a wide variety of conditions. In contrast to 

 these findings, no filament formation has been observed in floes of 

 pure myosin. 



EFFECT OF ATP 



When neutral ATP alone was added to flagellar gels, they became 

 filamentous in much the same way as they did with pH and electro- 

 lyte changes. In very fresh material washed free of electrolytes, fila- 

 ment formation was often very spectacular, the gel suddenly ex- 

 tending and streaming into long, thin webs, sometimes completely 

 dispersing in the liquid. A "streaming" network of this kind pro- 

 duced at a higher concentration of ATP is shown in Fig. 7. In this 

 particular specimen, the attenuation of the gel was so great that it 

 was a quarter of an hour before the network was stable enough to 

 permit photography with the rather slow plates that were used. After 

 storage for a day, this same preparation no longer became filamentous 

 on addition of ATP. 



In the presence of KC1, however, both actomyosin and flagellar 

 precipitates contracted when ATP (with added MgCl 2 ) was added. 

 A typical syneresis of actomyosin under these conditions is shown in 



i 



Fig. 7. Attenuated filamentous network from a gel from perch sperm 

 ffagella treated with 0.01 2M ATP. 



