THE MAMMALIA— MAN AND BEASTS. 



81 



aniraaus qui, dans I'etat ordinaire, ont la verge dirigee en arricre, comme les Rhin- 

 oceros, les Charaeaux, les Lamas, les Dromadaires, etc., s'accouploient en arriere; 

 mais il n'en est rien ; dans Terection, leur verge reprend sa direction en avant, et le 

 colt a lieu comme a rordinaire, mais, a la verite, avec plus de difficulte. Les singes 

 seuls s'accouplent a la maniere de I'homme, mais c'est a tort qu'on a pretendu que 

 I'elcphant en faisoit de meme, Selon BufFon, le male et la femelle du herisson ne 

 peuvent s'accoupler comme les autres quadrupedes ; il faut qu'ils soient face a face, 

 debout ou couches. Les rats s'accouplent en se raettant debout, ventre centre ventre. 

 Dans beaucoup d'especes chez lesquelles, comme les chats, les lions, les gerboiscs, 

 etc., le gland du male est muni de pointes cornees plus ou moins longues, et quelque- 

 fois dirigees en arriere, i'accoupleraent est tres-douloureux. Chez les chiens il dure 

 fort long-temps, ce qui est dii a une conformation particuliere du vagin de la femelle. 

 Dans d'autres, comme dans I'espece du taureau, il est termine en quelques sccondes. 

 Tantot la femelle se tient debout, tantot elle s'accroupit sur ses deus jambes 

 anterieures ; tantot le male se maintient a I'aide de ses deux memes membres 

 de devant, ou saisit la peau du cou de la femelle avec ses dents, etc. On a cru 

 long-temps qu'un sixierae ongle surnumeraire, qui se trouve au cote interne des 

 pieds de derriere des Echidnes et des Ornithorhinques otoit destine a faciliter I'ac- 

 couplement ; mais on a decouvert depuis peu que ces organes avoient un tout autre 

 objet, et que c'etoient des armes cmpoisonnces dont ces animaux se servoient contre 

 leurs ennemis; et c'est ce que M. de BlainviUe a confirme. (Desmarest in Npuv. 

 Diet, des Sciences Nat.) 



In some species of domesticated animals, especially in the Dog, copulation is main- 

 tained for a long time after the emission of the fecundating fluid ; whilst among the 

 greater part of the Birds, especially in the GalUn®, the union is instantanfously dis- 

 solved. It is always dangerous in the former cases to force a separation, which is 

 lometimes attempted, although opposed by the peculiar organization of the sexual 

 organs ; the intention of A'ature apparently being, by this extraordinary prolongation 

 of the union, to render conception more certain. " L'etroite conjonction paroit 

 destinee, dans le principe, aproduire I'irritation necessairea I'emissionde lasemence; 

 et le plaisir qui en resulte est le ressort qui determine le plus puissarament les animaux 

 a la propagation, quoiqu'elle paroisse douloureuse d'abord dans quelques especes, 

 comme dans le genre chat, dont les femelles poussent souvent alors des cris aigus. 

 Dans quelques oiseaux polygames aussi, comme les Faisans, Taccoupleraent paroit 

 etre uu acte plus violent que voluptueux ; car on voit les femelles redouter I'approche 

 du male, qui fait usage de sa force pour les y contraindre." (Yvart.) 



The older females of each species exhibit an attachment for the males, at an earlier 

 season of the year than those of a less advanced age. After conception, as has al- 

 ready been observed, the females, in general, repel the approaches of the male. In 

 all cases where the races are peculiarly ferocious, as in the Lion, Tiger, Panther, 

 and other large Cats, the females are the nrst to solicit the approaches of tho male. 

 Had this nut been the case, it is difficult to conceive in what manner their races 

 could have been continued. In species of a milder disposition, the males endeavour 

 to please the other sex, and often exhibit a strongly-marked fecHng of jealousy towards 

 their own. The Monkeys remain attached to one or two females, rarely to more. 

 Their union seems to be a kind of marriage; they require fidelity, are exceedingly 

 jealous, and severely punish their female companions, who are well-disposed to 

 coquetry, on finding them in company with other males. 



The phenomena of generation must, however, be considered in another point of 

 view, at once singular and surprising. It seems now beyond a doubt, that the power 

 enjoyed by male animals of continuing their species depends upon the presence in the 

 spermatic fluid of a certain kind of animalcules, which have thence received the name 

 of Zoospcrmata. The testicle, or secreting organ, is well known to be the means by 

 which the ovaria arc fecundated ; and it is remarkable, that within this organ alone 

 Zoospermata have been hitherto observed. 



All animals, before arriving at tha age of puberty, are incapable of reproduction, 

 and they are accordingly wholly destitute of Zoospermata. M. Dumas informs us 

 that he has made a considerable number of experiments upon young animals, and that 

 he found all of them to be destitute of Zoospermata. He particularizes the younn- of 

 the Rabbit, Calves, Foals, young Asses, Guinea-pigs only a few months old. Mice of 

 the same age, a great number of Norwegian Rats, with Pullets, young Ducks, and 

 even Frogs. The fluid extracted from their organs contained the same kind of irre- 

 gular globules which are found in the testicles of the Mule ; but it was wholly de- 

 prived of moving bodies, and nothing was found which could in any way approach to 

 the peculiar form of those animalcules proper to fertile animals. 



It is well known that animals become sterile at a certain period of life, varying 

 with the species. To ascertain whether the presence of these animalcules is essential to 

 fecundity, it becomes necessary to investigate whether very old animals possess them or 

 not. This, to a certain extent, has been done. M. Dumas exauiined a Stallion 

 aged twenty-five years, and which had been incapacitated throui^h age for about four 

 or five years, as well as some Dogs of a very advanced period of life. Their sexual 

 organs were perfectly healthy, yet he found them to be destitute of animalcules, and 

 the fluid within them resembled in every respect that of the young individuals ali'eady 

 mentioned. 



These facts serve to establish the importance of animalcules, and appear to show 

 that their presence is essential to the fecundating power of animals. 



"With the view of setting this interesLmg pomt beyond a doubt, many experiments 

 have been instituted. The spermatic fluid of a Dog was placed in two silver capsules 

 in equal quantities. La one of these, a metallic rod, polished at its extremity, was 

 plunged, m such a manner, that the rod and capsule might be placed in communica- 

 tion with the two surfaces of a Leyden phial, strongly charged. An electric spark 

 was then made to pass through the fluid, but not at its surface- After a few dis- 

 charges, the animalcules became entirely motionless, while the other capsule, which 

 had not been electrified, was animated with them as completely as it had been pre- 

 viously to the experiments, which did not last for five minutes. 



The result of this and other experiments, which cannot be detailed here, appear 

 to show that these animals possess irritability, and are destitute of the muscular 

 system of other animals. It is, however, certain that all male animals hitherto ex- 



amined, possess spermatic animalcules when in a state of puberty. Young indivi- 

 duals, as well as those that are aged, exhibit no traces of them, and even it is re- 

 marked, that Birds are destitute of spermatic animalcules, except at those particula*' 

 periods of the year which Nature has fixed for their procreation. The domestic 

 Cock and Pigeon, being fertile all the year round, are, of course, exceptions. 



These spermatic animalcules exist within the testicle in a state of complete perfec- 

 tion; they are transmitted to the deferential canals, without undergoing any altera- 

 tion during the transition. Neither their motion nor their form is influenced by the 

 mixture of fluids from the other glands, so that, on being emitted, they appear in thi» 

 same state as when in the spermatic vessels themselves. The spontaneous movement 

 of the animalcules is intimately connected with the physiological state of the indivi- 

 dual which supplies them. Each species possesses a species of animalcule, of a form 

 pecuhar to its^'lf, and no two species hitherto examined have the same kind of ani- 

 malcules, although they always remain the same in the same species. The electrio 

 spark kills them, but they are not aff'ected by the galvanic current, even when u-ed 

 in a degree of intensity sufficient to decompose water and the salts which it contains. 



Whatever opinion may be held as to the part performed by these animalcules^ in 

 the function of generation, it cannot be doubted that they exist solely in the essential 

 part of the generative organ, in all animals which do not reproduce by buds or off- 

 shoots. On the other hand, they are wholly wanting in animals incapable of gene- 

 ration, and their presence in the seminal fluid may thence be assumed as the index of 

 its fecundating power. 



With the exception of a few solitary instances of superfetation, it is always found 

 among the Mammalia, that the fecundation of the male refers only to one birth, being 

 that which next immediately follows the union of the sexes. On the contrary, with 

 the Birds, a single union may influence several successive broods. Thus, the domestic 

 Fowl will produce fertile eggs at tolerably remote periods of time, after having once 

 received the influence of the male. A young and vigorous Cock is adequate for fifteen 

 fowls, and serves to fecundate all the eggs they may produce during twenty days. Hence 

 one male may be sufficient to give existence in a single day to three hundred chickens. 



The phenomenon of gestation can only bo observed in the Mammalia and 

 other viviparous animals. The term Gestation^ from the Latin gestare, to carry, 

 denotes the period of time which elapses between conception and birth. Among 

 Birds and all other oviparous animals, a real gestation cannot exist, because the eggs 

 detach themselves from the ovaries, pass along the oviducts, and are deposited as soon 

 as they are formed. With these animals, gestation becomes superseded in general by 

 incubation, to which it is greatly analogous, and the former function may thus be 

 considered as little else than an internal incubation. The apparent design of Nature, 

 in both cases, is to favour the gradual development of the embryo or fcetus — the 

 first rudiment of the new animal resulting from conception. It is also observed, that 

 the rapidity of growth in the foetus, whether during the gestation of the viviparous 

 animals, or the incubation of the oviparous, always diminishes in proportion as the 

 foetus approaches the time appointed by Nature for its birth. 



The length of the period of gestation, like that of incubation, varies greatly among 

 the several genera and species. It further obtains certain accidental variations, which 

 appear to depend upon the age of the mother, her state of health, an increase or 

 diminution in the velocity of the circulation, the quantity or quality of the food, and all 

 those causes, derived from the influence of climate, soil, shelter, and thediflterentkindsof 

 treatment which these animals receive from Man. The period of gestation may also 

 be either shortened or prolonged, according to the temperature which prevails during 

 that interval. It is a matter of common observation among graziers, that two cows, 

 though fecundated on the same day, will yet produce at an interval of several weeks. 

 The variation among sheep under similar circumstances amounts to a few days, but 

 in general, this difference among domestic animals of the same species may extend as 

 far as twenty days. 



It commonly happens in all those species, where the individuals take a long time in 

 arriving at their full growth, that the period of gestation is considerably prolonged ; and 

 the converse is equally true ; for in all those species which are very precocious, the time 

 of gestation is extremely short. This rule is not, however, without many exceptions. 

 Thus, the Goat and Sheep are capable of reproducing at the age of two years, and have 

 commonly attained their full growth at this period, while their ordinary time of ges- 

 tation is about five months. On the other hand, a Lioness at the Menagerie du Museum, 

 in ISOl and 1802, seemed unfit for procreation before the age of two years, and yet 

 she produced after a gestation of 108 days only, or rather more than three months 

 and a half. 



The duration of gestation seems further to depend upon the comparative volume 

 of the species ; this rule, however, is by no means invariably preserved. Thus, the 

 Ass and Zebra, though less in volume than the Cow and Buffalo, employ less time 

 in performing this function than the latter species. 



It hence appears that the duration of gestation varies in different animals, and the 

 empirical laws deduced from multiplied observations are not without many exceptions. 

 By combining, however, the general organization of the Mammalia, with the time ne- 

 cessary for each q.nimal to arrive at its full growth, as well as with the comparative bulk 

 of the females, it is possible to obtain a general and definite result ; while the charac- 

 teristic thus obtained may, with propriety, be added to those which commonly serve 

 to distinguish the leading groups of Mammalia. Thus in RIan, nine months is the 

 well-known period of gestation. Among the Quadrumana, it is also nine months for 

 the larger species, but only seven for the smaller. In the Carnassiers, ge?tation en- 

 dures six months with the Bear; 108 days with the Lion; nine weeks with the 

 Arctic Fox (Cunis lagopus); from 55 to 56 days with the Cat; the same period 

 for the jMartens and Weasels ; from 62 to 63 days with the Dog ; and nine months 

 with the Morse. Those Mammalia which experience the shortest term of gestation 

 are unquestionably the animals belonging to the Order IMarsupialia. Among the 

 large Kangaroos, for example, the young are scarcely more than an inch in length, 

 when they first attach themselves to the breasts of their mother, although the full- 

 grown animal is at least five feet in height. Gestation is also of short duration in 

 the Rodentia, being only four months in the Beaver, one of the largest animals of 

 this order. It is still less iu the smaller Hodentia, being fium 30 to 40 days in the 



