461 



the normal environment of the sperms. The shape of the bowl and the 

 thickness of its walls is much changed. The contents of the bowl may 

 stain like the region below the mouth of the bowl and appears to be 

 very different from the walls of the bowl. 



Both in fixed material and in that treated with salts there is 

 often an appearance of an outer case or membrane that is difficult to 

 interpret. There may be halos about the sperms that hold them apart, 

 in masses, and may cause them to adhere to one another at times. It 

 seems that besids the parts of the sperm as above described, that is 

 the bowl and the arms united in a common region below the bowl, 

 there is a third element that is often invisible but that may be made 

 conspicuous by reagents and by stains. It acts like a mucous, or jelly, 

 enveloping the bowl and the coiled-up arms. Sometimes it is precipi- 

 tated, or changed, so that it seems to be a membrane and then it 

 may osmotically swell up and rupture in irregular forms suggesting a 

 plasmolyzing membrane made at the surface of a liquid mass about 

 and amongst the arms where coming into contact with reagents. On 

 the other hand the arms seem to have a connection with this mem- 

 brane and in some cases it seems as if the united arms, before un- 

 coiling, made a sort of membrane capable of being plasmolysed. 



In water the bases of the arms and their common origin, that is 

 the part of the sperm beneath the bowl, become so distended as to 

 reduce the vesicle to a relatively small object upon one side of a large 

 hollow sphere which may show little or no remnant of the arms pro- 

 jecting from it. The vesicle also is greatly changed and its contents 

 tend to ooze cut of its mouth as a lobed mass. 



Under certain conditions the swollen sperms may flatten out against 

 the slide, or cover glass, and spread out as wrinkled films with or 

 without remnants of arms strongly suggesting pteropodial expansions 

 of such thrombocytes as those of the coelomic liquid of Sipunculus 



An examination of stages of spermatogenesis in this crayfish leads 

 to the provisional acceptance of the view that the arms of the sperm 

 are made from the nucleus of the spermatid and that the cytoplasm 

 of the spermatid gives rise to the above halo of material that seems 

 to envelop the bowl and the arms. The vesicle is evidently a new 

 formation that comes to lie in the cup-shaped nucleus. It is inferred 

 that the nucleus becomes like a hollowed hand holding the vesicle like 

 an inverted bowl on the palm and enveloping all but the bottom of 

 the bowl by long, spirally coiled prolongations of the palm, fingers 

 that represent the arms of the sperm. 



