SEMEN. 



503 



further, the spores of the algae possess motion 

 by the aid of a ciliated investment *, or of a 

 single or manifold long whip-like fibre, until 

 they eventually become fixed, and develop 

 themselves into a new plant.f Such spores 

 as these may be found described and illustrated 

 in the well-known magnificent work of Ehren- 

 bcrg, classified as Infusoria under the groups 

 of Monadina, Volvocina, &c. 



Under such circumstances we may consider 

 ourselves perfectly justified in declaring every 

 attempt to prove the parasitic nature of the 

 spermatozoa, by the characteristic of their 

 peculiar motions, as futile and inadmissible. 

 Developement, structure, and composition are 

 the decisive characteristics in this respect, 

 and these prove the fructifying elements of 

 the semen to be mere elementary constituents 

 of the body in which they are formed. The 

 motions of the spermatozoa are therefore in 

 their essence identical with the above men- 

 tioned automatic motions of cilia, &c. But the 

 knowledge of the movement of the sperma- 

 tozoa will always be interesting and impor- 

 tant ; because, of all these phenomena, it is 

 undeniably most closely connected with the 

 locomotive motions of animals. 



We must not, however, lose sight of the 

 fact, that these motions are not possessed 

 in equal perfection by all spermatozoa, but 

 that in many cases they are scarcely visi- 

 ble, and hardly equal the motions of the 

 cilia. Indeed there are many spermatozoa 

 which are perfectly motionless, particularly 

 all those forms which owe their immediate 

 origin to a metamorphosis of the nucleus, or 

 of the wall of the primary cells. Only those 

 spermatozoa which have been produced by an 

 endogenous and new developement are capable 

 of independent motions, and even not every 

 one of these. No such movements have as 

 yet been perceived in the spermatozoa of 

 the Malacostraca (Isopoda and Amphipoda). 

 They appear motionless and rigid. The same 

 holds good with regard to the body of the 

 spermatozoa when it has a short, round, or 

 pyriform shape. It never then participates 

 in the motions, which are in such cases 

 altogether effected by the thinner, whip- 

 like, caudal extremity. It is different, how- 

 ever, with those spermatozoa which pos- 

 sess a cylindrical body. The body here par- 

 ticipates in the motion ; at least very fre- 

 quently, as, for instance, among the scaly 

 amphibia, among the birds (excepting among 

 the singing birds), &c. But the motions of 

 the body are less rapid, energetic, and various 

 than those of the tail. They are principally 

 limited to a bow-shaped curvature, similar 

 to the motion of the Vibriones, which, like the 

 Monadina, belong to the vegetable kingdom, 

 and may undergo a further developement into 

 fibrous fungi. 



* Vid. Unger, Die Planze im Moment der Thier- 

 wendung ; also Von Siebold, Dissert, de Finibus 

 inter Regnum Animale et Vcgolabile constituendis. 



f Frosenius, Zur Controverse iiber die Yenvaud- 

 lung vou Infusorien in Algeu. 



In order to observe the movements of the 

 spermatozoa properly, they ought to be in- 

 vestigated under different circumstances. On 

 putting a drop of thick semen from the vas 

 deferens under the microscope, a slow mo- 

 tion only can usually be observed in the 

 accumulated masses of spermatozoa. They 

 present an appearance as if they had some 

 difficulty in disentangling themselves from 

 the tough fluid by which they are sur- 

 rounded. On adding blood serum to it to 

 dilute the mass, the movement becomes more 

 lively,either instantaneously or gradually. Se- 

 parate spermatozoa writhe oncg or twice, turn 

 round on their axis, lash with their tail, and 

 creep about in all directions over the field. 

 The motion gradually imparts itself to greater 

 numbers. Here and there, simultaneously all 

 the individuals of a group begin to move; or 

 particular parts of the mass commence the 

 movement. The remainder perhaps exhibit 

 no motion, and sometimes this quiescent state 

 is permanent. 



if the movement of the spermatozoa be 

 rapid, it assumes, for the most part, an accu- 

 rate rhythm like a pendulum. The fili- 

 form tail vibrates like a whip, and the 

 small corpuscle or head follows the impulse. 

 Frequently a peculiar trembling, dancing, or 

 jumping is exhibited by the Litter when the 

 rest of the spermatozoon remains fixed and un- 

 moved. A serpentine creeping in all directions 

 is produced during a slow motion, and is 

 caused by an undulating contraction of the 

 caudal appendix. These undulating motions 

 are perhaps the most frequent which the 

 spermatozoa (and even the thread-like forms 

 which possess no visible body) present to our 

 view. They often move in one straight direc- 

 tion, without turning aside, and altogether in 

 such a way and with such a regularity as to 

 resemble the locomotive motions of many of 

 the lower animals. 



The same regularity is met with in the 

 motions of the long and rigid spermatozoa 

 with a spiral bod}' among the singing birds, 

 which very frequently turn rapidly round their 

 axis, and thereby advance with a screw-like 

 or boring movement. Pendulum-like lateral 

 motions nre but rare. 



Very peculiar and different are the motions, 

 of the spermatozoa in the Salamanders, which 

 usually lie wrapped up like a watch spring, 

 flat on a level. For a time they remain quiet 

 until suddenly, by fits and starts, a trembling 

 motion takes place, by which they turn them- 

 selves round in a circle, pretty nearly on the 

 same spot. Some few (as the Bombinator) 

 stretch themselves out, and travel with a 

 slow undulating motion over the field of the 

 microscope. The most remarkable pheno- 

 menon, however, consists in a peculiar wave- 

 like motion on the surface, and which is 

 solely caused by the rapid succession of un- 

 dulating motions. We have also perceived 

 a perfectly similar undulating motion in the 

 very long, coiled-up spermatozoon of Geo-r 

 philus, which is occasionally so powerful as 



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