33 



of inversion and those In the normal mature condition were 

 motinted under the microsoope and killed with this fluid in 

 order to determine its effect upon them. A considerable 

 amount of shrinking was observed, hut no decided change in 

 the relationship of the parts seemed to take place. Figures 

 86 and 87 were drawn from sperms exploded in distilled water, 

 fixed in Morgan's fluid, stained in thionin and eosin, dehy- 

 drated In alcohols, cleared in xylol and mounted in balsam. 

 The general relations of the parts is the same as in Figs. 81 

 and 82. The space between the everted tubule and the invert- 

 ed capsule seems to have shrunk relatively more than the in- 

 verted capsule. Having now observed the behavior of the 

 sperms under experimental conditions we may proceed to our 

 observations concerning the entrance of the sperm and the 

 process of fertilization. 



711. THE ENTRAHCE OF THE SPERM. 



Eggs were taken from the lumen of the ovary just after 

 the crab began to spawn, and were fixed in Morgan's fluid, 

 imbedded in paraffin and sectioned. A microscopic examina- 

 tion of these eggs showed the sperm in the act of entering 

 the egg. The best stain for the study of these sections is 

 thionin, for it stains the chromosomes in the mitotic figure 

 of the nucleus of the egg and the nuclear cup of the sperm a 

 deep blue. It stains the everted portion of the sperm faint- 

 ly and the food material, cytoplasm and egg-shell are unstain- 

 ed or only faintly stained. This treatment makes it possible 



