SEMEN. 



495 



it lengthwise, until they perforate the exter- The thickness, on the other hand, is compa- 

 nal enclosure at one end, and now gradu- ratively only slight, being most considerable 



in the centre, whence the fibre gets gradu- 



Fig. 383. ally thinner towards both ends. KoU&er 



describes, in the spermatozoa of Iphimedia 

 and Hyperia, a thicker cylindrical and oval 

 end, like a peculiar corpuscle. F. Siebold 

 does the same with regard to Asellus aqua- 

 ticus. We believe, however, that such an 



Fig. 384. 



Developement of the Spermatozoa in Mysis* 

 (After Frey and Leuckart.') 



ally project outwards (B, c). The number 

 of the fibres thus formed is generally limited 

 to one. We have, however, seen cylinders 

 which contained three or four (c). 



The formation of the spermatozoa in the 

 radiating cells of the other Decapods, in our 

 opinion, takes place in the same manner. 

 Judging from analogy with Mysis, at least, 

 we cannot share the conjecture of KolKker, 

 that the rays would simply drop off and 

 change into spermatozoa. It appears to us 

 much more probable that they are pro- 

 duced, as in Mysis, in the interior of the 

 cell, and that the growing out of rays is 

 merely a secondary event, caused by the 

 circumstance that the spermatozoa formed 

 in the interior urge the external membrane 

 forward with one end, and ultimately pene- 

 trate through it. The projection of the semi- 

 nal fibres, in Mysis, from the cylinder, has 

 indeed much the appearance of their growing 

 out into a thin and long appendix. 



Thus much respecting the remarkable semi- 

 nal corpuscles of the Decapods. We must 

 still, however, mention the circumstance that 

 the radiating cells in the lower division of the 

 testicles, or in the vas deferens, are generally 

 still enclosed by peculiar spermatophora, 

 like capsules, which possess a round or oval 

 shape, and are often attached, by means of a 

 solid peduncle, in great numbers, one behind 

 another, to one common round or flat jelly - 

 like mass. 



The spermatozoa in the other orders of the 

 Malacostraca, the Ampkipoda, and Isopoda, 

 are uniformly filiform. Their developement 

 takes place in the usual way, without the 

 intervention of radiated cells. 



The length of the spermatozoa, in most 

 cases, is very considerable : in Hyperia medu- 

 sarum '" ', in Iphimedia obesa '", in Idotea 

 tricuspidata -fa'", in Garnmarus Pnlex -fa"'. 



Spermatozoa of Gammarus Pulex. 



appendix (Jig. 384.), or this so-called corpus- 

 cle, is merely the adhering remainder of the 

 mother cell, from which the spermatozoa pro- 

 ject. Of this we have convinced ourselves 

 in Gammarus Pulex. It is certainly difficult 

 to distinguish the seminal fibre in the interior 

 of it, but it appears to us that our observa- 

 tions are sufficient to render doubtful the 

 interpretation of Kolliker, when we consider 

 that this corpuscle occupies so variable a 

 position with respect to the fibre, now lying in 

 the same line with it, and at other times 

 passing into it at a larger or smaller angle, 

 quite in the same manner that we have ob- 

 served in the cylinder of the seminal corpuscle 

 of Mysis. 



The variable shape of the body, which 

 Kolliker describes in Hyperia, and which we 

 have also found, although less remarkably so, 

 in Gammarus Pulex, might also speak in 

 favour of our opinion. 



The formation of the seminal fibres in the 

 Oniscidce, according to our observation, also 

 takes place in the interior of transparent 

 cells*, which reach ^-5'" T&T/" an d fill up by 

 their number the sacs of the testicles. As soon 

 as the developement of the spermatozoa has 

 commenced in the interior, the cells grow to the 

 extent of -", and in so doing assume an oval 

 shape. The contents then usually become 

 rather granular, but the windings of the 

 transparent spermatozoa can nevertheless be 

 recognised now and then. The vesicular 

 seminal elements of Gammarus Pulex, on the 



* The large egg- shaped corpuscles (of JL") which 

 possess, besides nucleus and nucleolus, dark gra- 

 nular contents, and which form the epithelium 

 of the vas deferens, but which are wanting in the 

 genuine seminal tubes, should not be confounded 

 with these seminal cells. Similar cells, only smaller 

 (of about 2g<5'") are likewise found in the spiders; 

 but, although they occur in the seminal cor- 

 puscles of the palpi, they are not in any way con- 

 nected with the production of the spermatozoa. 



