620 NATHAN FASTEN 



except the nucleus, which is hidden from view by the vesicle, V. 

 In the living state, the nucleus presents more or less of a finely 

 granular appearance. 



In low concentrations of various salts, such as NaCl, KCL, and 

 KNO3 (2 per cent and below), the sperm opened quickly. In 

 higher concentrations, the process of opening was somewhat 

 inhibited, and in strong concentrations (16 per cent) the sperm 

 became crenated and their opening up was very slow. Andrews 

 ('04), observed a similar behavior in the spermatozoon of Cam- 

 barus affinis. 



In many cases an interesting change was also observed in the 

 vesicle. In Ringer's solution and especially in water, the invagi- 

 nated edges of the vesicle straighten out in the manner indicated 

 in figures 68, 70 and 71. Evidently this transformation is pro- 

 duced by the osmotic changes undergone within the spermato- 

 zoon during the opening-up process. Now the question arises, 

 can this be the force which tends to drive the spermatozoon 

 into the egg during the process of fertilization? Koltzoff ('06), 

 Spitschakoff ('09), and Binford ('13), have also observed striking 

 changes undergone by the vesicle of the spermatozoon of other 

 decapods when subjected to various salt solutions. These 

 investigators are of the opinion that this force is the operating 

 factor in bringing about penetration of the ovum. 



6. Types of spermatozoa produced 



In Cambarus virilis a trimorphism of the spermatozoa is 

 found. Here five-, six- and seven-rayed types are produced 

 (figs. 108-110). The six-rayed type is the common and most 

 numerous form seen, being about four times as abundant as either 

 of the other two types. In Cambarus immunis a tetramorphism 

 of the spermatozoa exists. Here, besides producing the three 

 types found in Cambarus virilis, a fourth type of spermatozoon 

 containing eight rays is developed (fig. 77). This eight-rayed 

 form is very scarce and was observed in only two cases. The six- 

 and seven-rayed types are the forms most abundantly developed 

 in the testis of Cambarus immunis. 



