4-92 



SEMEN. 



it. A tail part we have, however, never been 

 able to discover in the spermatozoa of 

 Epeira. The form was uniformly cylindrical, 

 and of a tolerable thickness, similar to the 

 body in the spermatozoa of Clubiona. 



Quite the same mode of developement of 

 the spermatozoa we have also found in one 

 species of Theridimna. It can be traced 

 that it does not deviate at all in the forma- 

 tion of its spermatozoa from other animals. 

 But even the process of developement in Clu- 

 biona, which we have described, does not 

 exhibit any very material differences, which 

 is proved by the observation, instituted by 

 us in a small Dysdera, as also in Tegenaria 

 domestica. The mode of formation of the 

 spermatozoa, in fact, in these instances, occu- 

 pies almost the medium between the former 

 two. 



In Dysdera the spermatic cells containing 

 the nucleus (Jig. 375. A) measure only -5^'". 



Fig. 375. 



Spermatic cells of Dysdera, 



They are round at first until the nucleus 

 elongates itself, enlarges, and finally assumes 

 a kidney form, the external cell taking on the 

 same shape (B, c, D). One end of the nucleus 

 not unfrequently projects outwards (E), but 

 never in so striking a manner as in Clubiona. 

 The same changes of shape are exhibited in the 

 nucleus in the seminal cells of Tegenaria, 

 which measure ^o'"; they, however, never 

 lose their original round shape in the course of 

 the change. 



We have not been able to discover filiform 

 spermatozoa in the two last-mentioned spiders ; 

 but we nevertheless believe that they likewise 

 occur here, as in Clubiona. 



Respecting the spermatozoa of the Acarina, 

 we have as yet had but few observations ; it 

 appears, however, from the statements o* 

 V. Siebold, that similar stages of develope- 

 ment take place as among the genuine 

 Araneae. V. Siebold observed in the testicles 

 of Ixodes ricinus a large number of rather 

 long and large rods, which had an arched 

 curvature, and were enlarged at one end in a 

 clubbed shape. These rods were probably the 

 developed spermatozoa, and of a similar na- 

 ture to those we have found in Epeira. We 

 do not venture to determine whether the same 

 inference may be drawn with regard to the club- 

 shaped corpuscles, which V. Siebold discovered 

 in the Hydrachneae and Gamaseae. From the 

 description given, however, viz. of these cor- 

 puscles enclosing an oblong spot in the en- 

 larged end, and of their having been pro- 



duced by the metamorphosis of round nu- 

 cleated cells, we would rather suppose that 

 they were mere stages of developement of 

 the seminal cells, similar, perhaps, to the pe- 

 dunculated seminal corpuscles in Clubiona. 

 In addition to this we may mention that Dr. 

 Frey has communicated to us an observation, 

 from which it appears that Hydrachna like- 

 wise possesses spermatozoa of a filiform shape. 



The contents of the testicles in other 

 Acarinae (Trombidium, Zetea, Oribatea, Hop- 

 lophora, &c.), consist of small globules, which 

 in Bdeila assume a cylindrical shape. We are 

 inclined to consider such as the free nuclei of 

 seminal cells. We, at least, believe we have 

 seen in Phalangium that they were surrounded 

 by a cellular vesicle. 



Myriapoda. The remarkable spermatozoa 

 of the Chilopoda, which appear either as cylin- 

 drical corpuscles when in a developed state (in 

 Glomeris), or (as in lulus) as short conical 

 formations with a rounded point, are, accord- 

 ing to our observations, of the same nature as 

 the foregoing. 



In lulus terrestris, in which we have traced 

 the developement of these parts through all 

 phases, the primitive contents of the testicles 

 consist of a great number of small round cells 

 of 4^'", containing a very clear nucleus (of 

 about T io- /x/ ) which lies close to the cell wall, 

 and is highly refracting (fig. 376. A). In the 

 course of the developement, the nucleus en- 



Fig. 376. 



Spermatic cells of lulus terrestris. 



larges, and, in so doing, gradually 'converts 

 itself into a short cone (B, c, D), which, with 

 its point, extends beyond the surface of the 

 cell. For a time the cell continues to be at- 

 tached to the surface, until it dissolves, 

 rendering the seminal corpuscles free (Jig. 

 377.). The basal part of the developed 



Fig. 377. 



Spermatozoa of lulus terrestris. 



spermatozoa has a diameter of ^fa/" ^-5'", 

 and is rather protuberant and enlarged at 

 the edges. The height of the spermatozoa 

 is always less than the width, generally by 

 one half. 



On comparing the phenomenon in the form- 

 ation of these bodies with the first changes of 

 the nucleus in Clubiona, the analogy between 

 the two will clearly be seen. The relative 

 value only of the two is changed. The 

 corresponding conditions in Clubiona form 

 mere stages of transition necessary for fur- 

 ther developement, whilst the developement 

 in lulus does not proceed further than the 

 stage described. 



