194 FREDERICK G. E. PAUTARD 



shaken vigorously in a tall, stoppered cylinder. Centrifugal classifica- 

 tion followed as before without washing the finally sedimented fla- 

 gella with distilled water, although they were sometimes rinsed briefly 

 with buffered KC1. Unlike previous preparations, these flagella, illus- 

 trated in the optical micrograph in Fig. 2b and the electron micro- 

 graph in Fig. 2c, were mostly intact, with very little contamination by 

 small fragments or any appreciable quantity of membranes from the 

 head. Moreover, suspensions of these tails in salt solutions showed a 

 marked streaming birefringence. 



For x-ray diffraction studies, the flagella were suspended in distilled 

 water or salt solutions and dried down on glass blocks treated with a 

 water repellent. In earlier experiments, the salts left in the preparation 

 were removed after drying or, more often, the flagella were washed 

 with distilled water before the final suspension. Later, when buffered 

 salt solutions were used, the flagella were commonly dialyzed until 

 salt-free, and nondialyzable but soluble matter was dried down as well. 

 Films cast from these dispersions and solutions were cut into strips 

 about 1 mm across and mounted one on top of the other, usually on 

 stretching frames. The stacks of films were stretched in clamp or satu- 

 rated air and frequently examined under moist conditions. Diffraction 

 patterns were usually taken at 4 cm specimen-to-film distance in a flat 

 film camera using nickel-filtered CuK a radiation collimated by glass 

 capillary. 



Specimens for infrared analysis (kindly undertaken by Dr. K. D. 

 Parker) were cast as very thin films on glass and stripped as required, 

 or cast and retained on thin, infrared transparent sheets of polythene. 



GENERAL OBSERVATIONS ON THE MOTILITY OF FISH SPERMATOZOA 



In those sperm that have been studied, movement is of short dura- 

 tion. There appears to be little motion of the cells in seminal plasma, 

 but on dilution with water, the sperm disperse with a characteristic 

 writhing and billowing of the milt. This intense activity lasts for a mat- 

 ter of seconds only. Individual cells can be seen moving in a straight 

 line before they cease swimming and settle down to a brief period of 

 oscillation. The active swimming phase lasts for about 15 sec in the 

 trout, 12 sec in the perch, and 10 sec in the char, but the subsequent 

 oscillatory behavior persists for 2 or 3 min and sometimes longer in in- 



