GENERATION. 



459 



a lid somewhat like the cork of a phial, be- 

 tween which and the main body of the case a 

 spiral spring is interposed, so contrived that 

 when the case is immersed in water the spring 

 expands, forces off the top of the case, and 

 allows the seminal fluid to issue from the 

 interior. 



We must refer to the anatomical articles for 

 an account of the varieties of structure of the 

 male generative organs in different animals. 

 In some of those in which the vesiculae semi- 

 nales are wanting, as in the familiar example 

 of the dog, copulation is necessarily longer 

 than in others. Very little is known as to 

 the uses of the prostatic body or Cowper's 

 glands. See GENERATION, ORGANS OF. 



Spermatic animalcules. The most remark- 

 able circumstance undoubtedly which is known 

 respecting the spermatic fluid, is the almost 

 constant existence in it of an immense number 

 of minute moving bodies of the nature of In- 

 fusorial animalculae, the well-known and 

 celebrated spermatic animalcules, which, since 

 the time of their first discovery in 1677, have 

 excited the curiosity and speculative fancy of 

 many naturalists.* 



The spermatic animalcules have been found, 

 at one time or other, in the semen of almost all 

 the animals in which they have been sought 

 for,f but at that period of their life, and in that 

 season of the year only, when the animals to 

 which they belong are fit for propagation. 

 They are diminished in number, or even en- 

 tirely disappear, after very frequent emission 

 of the seminal fluid. They almost always 

 exist in the fluid secreted by the testicles, and 

 very often in that of the seminal vesicles, into 

 which they have doubtless been introduced 

 along with the fluid of the testicles. 



From these circumstances, as well as others 

 to which we shall afterwards advert, there is 

 good reason to believe, that the existence of 

 seminal animalcules in the male product is in 

 some way or other intimately connected with 

 the integrity of its fecundating property ; if not, 



* Haller states as his conviction, that Ludwig 

 Hamm (then a student at Leyden) was the first 

 discoverer of the seminal animalcules in August of 

 1677. Leeuwenhoek claimed the merit of having 

 made the discovery, in November of the same 

 year, and in 1678, Hartsaker published an account 

 of them, professing to have seen them as early as 

 in 1674. A great deal has since been written re- 

 garding them. Needham, Buffon, Der Gleichen, 

 Spallanzani, Prevost and Dumas, and Wagner, 

 may be mentioned as those who have devoted 

 most attention to these curious little animals. Our 

 remarks are taken chiefly from the investigations 

 of the three last authors, as well as from original 

 observations. 



t The class of fishes are stated by Messrs. Pre- 

 vost and Dumas to form an exception to this 

 remark, these observers not having been able to 

 discover any seminal animalcules in the seminal 

 fluid of fishes ; but they are stated to have been 

 seen by older authors (see Haller's Elementa, vol. 

 vii. p. 521); and from the latest investigations it 

 appears that they exist, though of a form different 

 from the spermatic animalculae of most other ani- 

 mals. The author has seen them very clearly in 

 the seminal fluid of the Perch, and one or two 

 other fishes. See Fig. 51, p. 112, vol. ii. 



as some are inclined to hold, the essential cause 

 of it. 



The form, appearance, and size of the semi- 

 nal animalcule are different in almost every 

 different animal, and in each species of the 

 more perfect animals the kind of animalcule 

 seems, like that of Entozoa, to be constant and 

 determinate. While, therefore, these little crea- 

 tures, by their minute size and their general 

 structure and appearance (so far as these are 

 known), are distinctly animals of the infusorial 

 kind, their residence in other living animals 

 entitles them to be classed among the Entozoa. 

 Baer considers them as most nearly allied to 

 the Cercaria among the Infusoria, and gives 

 them the very appropriate name of Sperma- 

 tozoa. 



In what we have hitherto said of the seminal 

 animalcules, we have drawn our description 

 principally from what has been observed in 

 quadrupeds and birds, but they differ consi- 

 derably from these in some of the inferior 

 animals. Czermak* holds that these various 

 forms may be referred to three principal heads, 

 viz. : 



1 . Cephaloidea, merely rounded bodies with- 

 out tails, existing in fishes and some Annelida. 



2. Uroidea, thread-like, in Mollusca, Am- 

 phibia, and some birds. 



3. Cephal-uroidea, consisting of a globular 

 and a tail part, in Mammalia, Birds, and In- 

 sects. 



The first of these kinds of Spermatozoa are 

 like the Monades among Infusoria, the second 

 resemble the Vibriones, and the third, as has 

 been already remarked, the Cercaria. 



It is important to remark that, in so far as 

 has as yet been ascertained, the form and size 

 of the spermatic animalcules do not bear any 

 intimate relation to the animal in which they 

 exist, nor to the ova of the female. In respect 

 of form, Messrs. Prevost and Dumas state that 

 the head is usually of a round lenticular shape 

 in quadrupeds, while in most birds it is of a 

 long oval shape ; but in some birds the form is 

 the same as in most quadrupeds. The semi- 

 nal animalcules present nearly the same ap- 

 pearance in man and in the dog. Various 

 markings are represented in the cephalic por- 

 tion of the animalculae of some quadrupeds by 

 Messrs. Prevost and Dumas, but these, we 

 are inclined to believe, are not constant, and 

 are appearances which have arisen from acci- 

 dental circumstances. 



In respect to size, there appears to be still 

 a greater want of correspondence. The semi- 

 nal animalculae are said not to be larger in the 

 whale than in the mouse. They are very much 

 larger in Insects, Mollusca, and others of the 

 lower animals than in Man. In the snail they 

 are fifty-four times longer than in the dog, and 

 considerably larger in the mouse than in the 

 horse 



The following table exhibits approximative^ 

 the sizes of the spermatic animalculae of some 



* Beytrage zu der Lehre von der Spermatozoen, 

 2 n 2 



