SPERMATOZOA. 



longer and more pointed, itself forms the head. It is remarkable that 

 the ova are in no way separated from the spermatozoa, but lie imbedded 

 in the spermatic mass like eggs packed in sand*." 



(61.) The multiplication of marine sponges, however, is effected in 



* The Spermatozoa, until recently considered as animalcules, generally present 

 themselves under the form of long slender filaments or corpuscles, the shape of which 

 varies to a remarkable extent, and nevertheless is so constant in individuals belonging 



Fig. 13. 



to the same species that it is frequently 

 possible to identify by their form the 

 particular creature to which each mo- 

 dification is peculiar. Generally speak- 

 ing, among the higher animals the 

 Spermatozoa are found to consist of 

 an extremely attenuated linear body, 

 either filiform throughout or swollen 

 and enlarged at one end, so as to pre- 

 sent something like the appearance of a 

 microscopic tadpole (fig. 13, 1). They 

 are exceedingly minute, seldom exceed- 

 ing a line in length, but much more 

 generally of far smaller dimensions, so 

 that the highest powers of the micro- 

 scope are requisite for their examina- 

 tion. These microscopic atoms may 

 be regarded not merely as abounding 

 in the seminal secretion of all animals, 

 but in fact as constituting that im- 

 portant agent, the presence of a fluid 

 or liquor seminis appearing, when re- 

 garded in a physiological point of view, 

 merely the vehicle in which the active 

 Spermatozoa are suspended. 



Until very recently these minute 

 bodies were regarded as individual 

 animated creatures ; and many authors 

 have fancied that several forms of 

 them at least presented a somewhat 

 complicated organization, such as an 

 intestine, gastric sacculi, and even gene- 

 rative organs 1 . More recent researches have, however, satisfactorily proved that 

 they are in all cases composed of a uniform homogeneous substance of a yellowish 

 colour, in which no traces of complexity of structure are discernible. Their move- 

 ments, however, are in most cases exceedingly vivacious ; and were it not for the 

 now well-ascertained fact that many other constituent elementary tissues, both 

 animal and vegetable, exhibit equal activity even long after their separation from 

 the organisms to which they belong, we might still be tempted to assign to them 

 a much higher position in the scale of vitality than that to which they are really 

 entitled. The motions of the Spermatozoids are, however, evidently only com- 

 parable to the automatic movements of cilia, and the relationship which they bear 



This figure represents the several stages of evo- 

 lution of the Spermatozoa in the common creeper 

 (Certkia familiaris), magnified about a thousand 

 diameters. I, an adult Spermatozoon, taken from 

 the orifice of the vas deferens; a, b, c, seminal 

 granules, which are probably nothing more than 

 altered epithelial cells ; d, e, f, cysts or vesicles en- 

 closing one or more round granular globules ; g, a 

 similar cyst containing, besides the two globules, a 

 finely-granular mass, in which the Spermatozoa 

 may be seen to form ; h, the cyst, still containing 

 finely-granular matter, has assumed an oval form, 

 and the bundle of spermatic animalcules, increased 

 in size, lies bent up within it ; i, a cyst still more 

 developed ; the involucrum, pear-shaped, covers the 

 bundle of animalcules where their spiral extremities 

 lie; k, a cyst arrived at maturity, still covered by 

 the involucrum. (After Wagner.) 



1 Vide Leuwenhoeck, vol. iv. pp. 268, 284 : Ehrenberg, Infusionsthierchen, p. 465 : 

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



