EXPLOSION OF SPERMATOZOA OF LOPHOPANOPEUS BELLUS. 295 



is the same as that brought about by tannic acid. The sperma- 

 tozoa are soon killed and stained a yellowish-green. 



(j) Chromic Acid. This produces a similar result to that 

 obtained with either tannic or picric acids. Here the sperma- 

 tozoa are fixed a yellowish-brown. 



DISCUSSION. 



A careful examination of the data presented in this paper 

 shows quite clearly that a lowering of the osmotic pressure in 

 the medium which surrounds the spermatozoa is responsible for 

 their explosion. In this respect the present research bears out 

 what Koltzoff ('06) first suggested for the explosion of the 

 spermatozoa of other decapods. Also, Binford ('13) in Menippe 

 mercenaria and the present writer in Cambarus virilis (Fasten, 

 '14), and Cancer magister (Fasten, '18), have found that osmotic 

 pressure accounts for the explosion of the spermatozoa. In the 

 light of all this accumulated evidence it seems quite certain that 

 the stimulating agent w^hich brings about the explosion in the 

 spermatozoa of the Decapoda, is one which reduces the osmotic 

 pressure in the medium that surrounds them. 



Since this is the operating factor, the question which naturally 

 suggests itself is where in the Decapoda is such a stimulating 

 agent produced? The writer is strongly of the opinion that the 

 mature gonads of the female decapod produce some chemical 

 substance which, when it comes in contact with the spermatozoa, 

 brings about their explosion. The experiments with the ovarian 

 fluids seem to point to such a conclusion. The work of Koltzoff 

 ('06) and Binford ('13) also suggests a similar conclusion. 



Concerning the function of the explosion, it, undoubtedly, 

 acts as the force or the motive power which drives the sperma- 

 tozoon into the egg during the process of fertilization. What 

 parts of the spermatozoon actually penetrate the ovum during 

 fertilization is still a debated question. Koltzoff ('06) and Spits- 

 chakoff ('09) are in agreement that the nuclear cup (derived 

 from the nucleus of the spermatid) is the only structure which 

 enters the ovum. Binford ('13), on the other hand, claims that 

 the everted vesicles (cytoplasmic structures) of the exploded 

 spermatozoon are driven into the egg, whereas the nuclear cup 



