SEMEN. 



489 



number and size of the latter is generally 

 much smaller than in the lower part. It fol- 

 lows, of course, that the size of the mother 

 cells themselves is influenced by the size and 

 number of their contents : wherever the 

 number of the enclosed vesicles is small, 

 the cyst never attains a considerable size. 

 In Culex, for instance, it seldom exceeds 



The vesicles surrounded by the cyst are as 

 clear as glass, and, when uninjured, contain an 

 entirely homogeneous material, which, how- 

 ever, appears granulated on being treated with 

 water, and then also it sometimes forms a 



Fig. 368. 



Developing cells of the Spermatozoa of Culex. 



large nucleus-like body in their interior. In 

 each of these vesicles, as V. Siebold* has shown, 

 a single spermatozoon is usually produced 

 (fig. 368.). It attaches itself in numerous 

 windings to the inner surface of the cell 

 wall, until it has reached its full develope- 

 ment. In the mean time the vesicle loses 

 its original round shape, becoming stretched, 

 and assuming the most various forms (Jig. 

 369.). At last the vesicle bursts at some 

 place, and allows the spermatozoa to come 

 forth. (Fig. 370.) 



The spermatozoa having thus become free, 

 group themselves together into regular bun- 

 dles, still enclosed by the mother cell of the 

 vesicle of developement. This at least seems 

 to be the case invariably wherever the cyst 

 persists long enough. It, however, some- 



Fig. 369. 



Spermatozoa in the interior of the vesicles of develope- 

 ment of Nepa cinerea. 



times disappears at an early period, as, for 

 instance, according to tM, in Musca, in 



* Tiber die Spermatozoiden der Locustinen, A. 

 a. o. S. 1. 



which case the vesicles of developement form 

 loose groups, as in Amphioxus. 



Fig. 370. 



Spermatozoa partially expelled from the vesicles of 

 developement of Nepa cinerea. 



The bundles in many cases disperse as 

 soon as the mother cells are destroyed. 

 But it still more frequently occurs that 

 these bundles survive the existence of the 

 cyst, the remainder of which then covers for 

 some time to come (as in the singing birds, 

 &c.) the anterior end of the bundle in a 

 cap-like form. (Instances Coleoptera, Neu- 

 roptera, &c.) In this part, which is ge- 

 nerally lengthened, the separate spermatozoa 

 lie together in a remarkably dense manner, 

 being almost united together into one com- 

 mon mass. 



It is different, however, in most cases with 

 the posterior division of the bundles (Jig. 

 37 1 . A.), where the separate fibres start away 

 from each other. In this way the usual pear, 

 club, or retort shape of the spermatozoa 

 bundles is produced.* It is but rarely the case 

 that the spermatozoa present, in their whole 

 length, an arrangement similar to that which 

 is usual at the anterior end. The whole 

 bundle of spermatozoa then appears as (Jig. 

 371. B) a homogeneous structure, and might 



Fig. 371. 



Bundles of Spermatozoa, A, from the testicle of Sta- 

 phylinus erythropterus ; B, of St. cyaneus. (After 

 Siebold.') 



readily be taken for a single colossal sperma- 

 tozoon, if the observation of the develope- 

 ment had not taught us otherwise. Of this, 

 however, we may convince ourselves by ma- 



. 



testicle of Paludina vivipara, which V. Siebold de- 

 scribed as a second form of spermatozoa Miiller's 

 Archiv. 1836, S. 246. 



