SEMEN. 



491 



itself, and then becomes a short, and gene- 

 rally curved, cylinder (B), one end of which 



Fig. 372. 



BCD 

 Seminal cells in the testicles of Clubiona claustraria. 



is frequently club-shaped. The nucleus 

 at the same time generally urges itself to- 

 wards the outside, its point penetrating 

 through the external cellular membrane. The 

 projecting part of the nucleus generally ap- 

 pears like a protuberance at the margin of 

 the cell, the greater part of it being still situ- 

 ated in the interior (c, D). In some cases, 

 however, it breaks forth in its whole length 

 (E). It then looks like a peduncle-shaped 

 appendix. 



We have not been able to discover 

 further stages of develope- 

 Fig. 373. ment in the interior of the 

 testicles ; but we have suc- 

 ceeded in detecting, besides 

 the already mentioned cor- 

 puscles, a number of dis- 

 tinct linear fibres of -ft/" 

 sV" (,/% 373.) m tne spoon- 

 shaped capsules on the pal- 

 pi of the males, which, no 

 doubt, were developed sper- 

 matozoa. The anterior half 

 of these was generally bent 

 in an arched cylindrical form, 

 and thicker than the pos- 

 terior tail-like part. Very 

 similar, only rather longer, 

 Seminal fibres of seminal fibres are likewise 

 Clubiona. found in the seminal capsules 

 of the palpi in a species of 

 Tetragnathus. 



It can hardly be doubted that these fibres 

 have originated from the previously described 

 spermatic cells. The changes of form 

 to which the nucleus is subjected in the 

 course of developement present a gradual 

 approximation to this form of spermatozoa, 

 at least to the form of the anterior thick- 

 ened corpuscles, with which the nucleus 

 moreover corresponds in its physical cha- 

 racters. In order to render the metamor- 

 phosis of the nucleus into spermatozoa com- 

 plete, it certainly is necessary that the 

 external cellular wall should disappear; but 

 this is a general rule in the developement 

 of spermatozoa, and probably also takes 

 place here, although we cannot furnish any 

 immediate proof of it. It must, however, 

 appear remarkable that we have never met with 

 developed spermatozoa in the testicles them- 

 selves. We could only trace in them cells of 

 developement, formations which, besides the 

 spermatozoa, also occur in the capsules of the 

 palpi. The question might be asked whe- 

 ther this would not render the inference 



justifiable that the spermatozoa only at- 

 tained their final developement at the latter 

 spot, and therefore at a distance from the 

 place of their formation. From our described 

 observations we cannot yet venture to decide 

 this question with certainty. The circum- 

 stance is, at all events, very remarkable, and 

 would be the more so in case V. Siebold's 

 statement that the cellular seminal corpuscles 

 are to be met with even in the receptacula 

 seminis of the female spiders, were to receive 

 confirmation. 



In our description of the developement 

 of the spermatozoa in Clubiona we have left 

 the question undetermined, whether they ori- 

 ginate directly from a metamorphosis of the 

 nucleus, or through endogenous formation 

 in the interior of it. We have not been 

 able to arrive at any decisive result respecting 

 it with regard to Clubiona, although the latter 

 appeared to us more probable from analogy. 



Of some importance in this respect are our 

 observations on the developement of the 

 spermatozoa in a large species of Epeira. The 

 seminal cells measure ( Jig. 374. A) T &/", the 



Fig. 374. 



Developement of the spermatic cells of Epeira. 



nucleus which they contain T J</". The cells 



are enclosed in larger cysts (of 'yfo/" ^'") ; 



but besides these there is also no want of in- 

 dividual solitary cells. 



The most interesting circumstance con- 

 nected with this is, that the spermatozoa are 

 produced quite distinctly in the interior of 

 the nucleus of the spermatic cells. At 

 first they are lying (B) like a bent cylinder at 

 the interior surface of the wall, so much bent 

 that both ends nearly touch each other. We 

 have never perceived a change of shape in the 

 nucleus, nor does the same ever or any where 

 penetrate beyond the cell. It constantly re- 

 mains round, and in the interior of the cell, 

 until it is dissolved, which takes place pretty 

 rapidly after the formation of the spermatozoa. 

 The spermatozoon now arrives in the cavity 

 of the cell (c F), where it increases in size 

 ( to T&O'")- It; usually exhibits here some 

 slight and irregular windings, which sometimes 

 change the form of the cell into an oval. The 

 spermatozoon only becomes free afterwards, 

 when the membrane of the cell has disap- 

 peared. It is only if the external cyst happens 

 to persist that the spermatozoa still remain 

 enclosed for a time (H), but always in a 

 greater number, which naturally is equal to 

 the number of the cells formerly contained in 



