502 



SEMEN. 



in many glandular cells of the insects gra- 

 dually assumes a remarkable ramified shape* ; 

 and that it even converts itself in other cases 

 into peculiar fibrous formations into the 

 so-called nuclear fibres (Kernfasern).-}* Still 

 more remarkable is the metamorphosis of 

 the nucleus in the developement of the so- 

 called prickle or nettle organs those in- 

 teresting microscopical formations, which are 

 so frequently imbedded in the skin of the 

 lower animals (e.g. Polyps and Medusae), 

 and which present so great a similarity to 

 certain forms of the seminal fibres, that they 

 were even taken for such by one of us on 

 their first discovery. Kb' Hiker' s^. observa- 

 tions, as well as our own more recent 

 ones, instituted upon Hydra, convince us 

 beyond doubt that it is the nuclei of cells 

 which gradually metamorphose themselves 

 into the capsules of the prickles, and which 

 ultimately become free through the dissolu- 

 tion of the cell membrane surrounding them. 

 The same genetic process therefore takes 

 place here in every essential point of view, as 

 that by which the formation of the sperma- 

 tozoa in the Chilopoda is effected. But the 

 developement of the prickles is never limited 

 to this metamorphosis of the nucleus. There 

 is formed at the same time in its interior 

 a peculiar linear or fibrous part, which how- 

 ever constantly enters into combination with 

 the persistent external vesicle of the nuclei 

 or with the capsule. Thus we may see that 

 the formation of the prickles is closely con- 

 nected with that scheme which we have laid 

 down as a formula for the developement of the 

 spermatozoa. It occupies the medium be- 

 tween the second and third mode of de- 

 velopement of the spermatozoa established 

 by us. 



On examining the external coverings of 

 Hydra, we shall readily be enabled to con- 

 vince ourselves of the formation of these 

 organs. The most different stages of de- 

 velopement may here be seen, viz. developed 

 prickles, either free or still enclosed by a 

 cell membrane, from which the organ it- 

 self, and especially the fibre enclosed in its 

 interior, recedes more and more, until it 

 finally appears as a mere simple nucleus. 

 In several Planariae the organs are con- 

 tained, in an imperfect state, in considerable 

 numbers in one common cell. The nuclei 

 in the interior of the cells have therefore 

 multiplied here, as in the seminal cells of the 

 vertebrata. 



Organization of the spermatozoa.. At the 

 period when the spermatozoa were still con- 

 sidered as individual animated creatures, it 

 was natural that those qualities should be 

 sought for, which distinguish animals gene- 



* According to the discovery of Frey and Leuc- 

 kart (Wagner's Zootomie, ii. p. 61.), which sub- 

 sequently, has also been made by H. Meckel (Mttl- 

 ler's Archiv. 1846, S. 26.). 



f Vid. Henle (Allgemein. Anat. S. 193.) and 

 Zwicky (Metamorphose der Thrombus). 



I R. Wagner in Weigmann's Archiv. 1835. 



rally; and it was frequently asserted that the 

 distinct traces of an internal organization 

 had been found in them. Even Leuwenhoek*, 

 the oldest observer of these structures, de- 

 scribes in the body of the spermatozoa of 

 the ram and of the rabbit, indications which 

 were subsequently interpreted by Ehrenberg -f- 

 and Valentin I to be intestines, stomachic 

 vesicles, and even generative organs. Other 

 histologers, for instance, Schivann and Henle, 

 thought themselves justified in calling a dark 

 spot, which shows itself occasionally in the 

 body of the spermatozoon in men, but which is 

 decidedly a mere accidental formation, as a 

 suctorial cavity. But all these statements are 

 now no longer believed in, as our present 

 knowledge of the developement of these form- 

 ations has entirely removed the idea of their 

 parasitic nature. Indeed the subject requires 

 no further refutation, as an unprejudiced ob- 

 servation will prove that the spermatozoa are 

 every where void of a special organization, 

 and consist of an uniform homogeneous sub- 

 stance, which exhibits, when examined by the 

 microscope, a yellow amber-like glitter. The 

 above mentioned investigators have by this 

 time undoubtedly seen their error. 



Motions of the spermatozoa. The opinion 

 of an internal organization of the developed 

 seminal elements was not a little supported 

 by the various remarkable phenomena of 

 motion, which were frequently perceived in 

 them. In former times, when people had no 

 idea of the existence and extent of the so- 

 called automatic phenomena of motion, which 

 take place without the intervention or in- 

 fluence of the nervous system ; when nothing 

 was known of the motion, very similar to a vo- 

 luntary one, which exists even in plants ; this 

 movement was certainly calculated to place the 

 independent animal nature of the spermatozoa 

 almost beyond a doubt. But it is different 

 now. We now know that motion is not an 

 exclusive attribute of animals, and that an in- 

 ference respecting the animal nature of the 

 formations in question, however similar the 

 motion observed in them may be to that of 

 animal organizations, is a very unsafe and 

 venturesome one. We know that certain 

 elementary constituents, animal as well as 

 vegetable, possess a power of movement, and 

 that they even retain it for some time after 

 having been separated from the organisms to 

 which they belonged. We only here need 

 remind our readers of the so-called ciliated 

 epithelia, the severed cells of which swim 

 about in the fluid surrounding them, and 

 which, when in this state, have not unfre- 

 quently, and that even quite recently, been 

 considered as independent animals}); how, 



* Opera, vol. iv. pp. 168. 284. 



f Infusoriensthierchen, S. 465. 



j Nov. Act. Acad. Leopold, vol. xix. p. 239. 



For instance, Nordmann , has described the 

 severed ciliated cells from the sails of the larva? 

 of Nudibranchiata as parasitic Infusoria (Cos- 

 mella hydrarhaoides). (Versuch einer Mono- 

 graphic der Tergipes Edwardsii. Petersburg!*. S. 

 97.) 



