THE MAMMALIA.— MAN AND BEASTS. 



57 



may differ greatly, but aJways vrlthin certain well-defined limits. We may perhaps 

 consider the Calmuck variety, with very long, thick, and white hair, as the greatest 

 deviation from the original type. 



With the Domestic Hog, the extreme points of variation must be placed in 

 its soft and pendant ears, the smallness of its tusks, and the union of its hoofs. 

 This animal appears to depart most widely from its original form, when domesticated 

 in the warmest countries ; and then the variations in size and shape are innumer- 

 able, and its colour usually changes to white. That variety of the Hog with un- 

 divided Hoofs, observed long ago by Aristotle, is sometimes found in England ; and 

 in Normandy there is said to be a race of Hogs with the fore legs much shorter than 

 the hinder. 



It is, however, in the Dogs that varieties are most striking and important. Man 

 has transported these animals into every part of the globe, and the extent of his power 

 is seen in the extraordinary differences of their forms. As their unions may be re- 

 gulated entirely by the will of their master, and as the connate rarieties of 

 individuals are readily transmitted to their offspring, we find among them singular 

 deviations from the original type. Not only is their colour infinitely various, but 

 their hair becomes more or less abundant, and sometimes it is wanting altogether. 

 The height of some Dogs is five times as great as that of others, and their bulk may, 

 therefore, be more than one hundred fold. These are not the only differences. They 

 seem to be acutely susceptible to all those circumstances which affect the growth of 

 the different parts of the body. The forms of their nose, ears, and tail; the relative 

 height of their limbs ; the progressive development of their brain ; and the form of 

 their skulls, are alike affected by these sources of vai'iation. Sometimes the head is 

 slim, the muzzle slender, and the forehead flat. Often the face is fore-shortened, 

 and the forehead projects. Indeed, the differences between the French Matin Dog 

 and the Water- Spaniel, between the Greyhound and the Bull Dog, are more strongly 

 marked than those among many wild animals of the same genus, but of different 

 species. It is unquestionably in the varieties of the Dog that we see the highest 

 deo-ree of deviation yet ascertained to prevail among the individuals of any species 

 throughout the entire Animal Kingdom. . 



Of all the characters which the domesticated animals possess, it may be observed 

 that the colour of the hair and skin is the most hable to variation. Being placed 

 externally, this part of the body is exposed more than any other to the influence of 

 outward causes of change. The hair of the different Dogs exhibits this natural ver- 

 satility in a remarkable degree with respect to colour, quality, length, and arrange- 

 ment. In cold climates the Dogs have usually two kinds of hair; the one, being 

 short, fine, and woolly, immediately covers the skin, while, in the other, the hairs arc 

 long and silky. It is the latter kind of hair which imparts the coloured appearance 

 to the animal. In tropical climates, the fine and warm woolly hair becomes obli- 

 terated, and at length wholly disappears. The same thing happens in our houses, 

 when Dogs are protected from the changes of weather and the severity of winter. 

 The skin of the Barbary Dog is naked and oily ; the Bull Dog, the Mastiff, the 

 Greyhound, and the CarUn, have the hair short and smooth. It becomes longer in 

 the Shepherd Dog, the Wild Dog of New Holland, the French Matin, and the 

 Iceland Dog; it is very long in the Wolf Dog, the Spaniels, and especially in the 

 French Bichon, where it sometimes reaches nearly to the ground. Again, if the hair 

 be vievTed in respect to its quality, we find at least as many shades of difference. The 

 Shepherd Dog, Wolf Dog, and the Griffon, have coarse hair, while in the French 

 Bichon, some Water- Spaniels, and the Great Dog of the Pyrennees, it is both silky 

 and soft. In some it is straight and smooth, in others woolly and curly. Many 

 races have the body clothed entirely with long hair, while on the head and limbs it 

 is perfectly thin and smooth. Others, on the contrary, have the head and neck fur- 

 nished with a mane, and the remainder of the body is covered with short hair. The 

 Wolf Dof is an instance of the former kind, and the Lion Dog of the latter. In 

 these respects, we find in the hair of Dogs all those variations of quality and quantity 

 which can be found in the several genera and species of the Mammalia. Their co- 

 lours may be white, a deeper or paler brown, fa\vn, or black. Some Dogs are seen 

 entirely of one of these colours, but most frequently the tints are distributed irregu- 

 larly in spots, which may be either large or small. Sometimes these spots have a 

 tendency to become symmetrical ; at other times the longer hairs are of a different 

 colour from the short ones, and then the joint effect of the two colours produces dif- 

 ferent shades, according as the white, black, fa\vn, or brown, predominates. Thus, 

 we may see Dogs with hair apparently resembling that of the Wolf, and upon a closer 

 examination this is fovmd to proceed from the mixture of white, fawn, and black 

 hairs ; or more rarely the general effect may produce a gray slate colour. These co- 

 lours are not connected with any particular variety, nor does it necessarily follow that 

 Dogs of different colours must be further distinguished by the forms of their heads, 

 the quality of their hair, or the proportions of their bodies. It usually happens, in 

 all these cases, that when care is taken always to unite individuals of the same colour, 

 form, and size, that the race perpetuates itself. It is from the constant union of indi- 

 viduaJs having the same, or nearly the same, colour that the Danish Dog, Grey- 

 hound, Bull Dog, and Mastiff, are fawn, the Shepherd Dogs are black, the Wolf Doo-s 

 white, and the Gallic Hound, the Braques, Bassets, and Spaniels, have black spots 

 upon a white ground ; but when this precaution is not observed, the colours of the 

 above-mentioned Dogs will be modified in proportion to their degree of admixture 

 with other races. However, the connate modifications of colour, as well as tha 

 more important ones of shape and size, usually end in becoming hereditary, when they 

 are not counteracted by some neutralizing cause. 



Thus we find, upon the whole, that the more important variations of the JIammalia 

 may be ranged under the following heads : — 



1. The skull and face may be shorter or longer, broader or higher; the forehead 

 may be elevated as in the Wild Boar, or depressed as in the domestic Ho». Thus 

 the head of the NeapoHtan Horse differs remarkably from that of Hungary and 

 Transylvania in the shortness and breadth of its lower jaw-bone. Camper also re- 

 marked, that the lachrymal depresaions (jnvea lachrymales), which can be clearly 

 observed in the Wild Bull, had disappeared by degeneration in the domestic Os. 



2. The general figure and proportion of the limbs may be altered to a most re- 



id 



markable extent. We sec striking instances of this variation on comparing the 

 Syrian and Arabian Horses with those of the North of Germany and the Shetland 

 Isles. 



3. In stature there may be a singular disparity ; thus, the Hogs transported to the 

 Island of Cuba acquire a size nearly double that of the common European Pig ; and 

 a very considerable growth takes place among the Wild Cattle of Paraguay. 



4. The texture and quality of the Hair may vary from the soft wool of the Thibet 

 Sheep to the dense and almost rigid hair of the Ethiopian variety. In Normandy, 

 the bristles of the common Pig lose all their stiffness. But the most singular in- 

 stances of variation in the hair are effected by the cUmate of Anatoha, where this 

 cause equally affects different species of Mammalia, and transforms the short fur of 

 our Cats and Rabbits, as well as the wool of our Sheep, into the long and silky fleece 

 of the Angora varieties. 



Lastly, the colour of the Hair may vary from black to white through all the shades 

 of brown or red. The fleeces of Angora often assume a silvery whiteness. Indeed, 

 we have only to look around us to see innumerable instances of diversity in the colours 

 of our domestic animals. 



GENERAL REVIEW OF THE MAMM,4LTA CONTINUED. 



Perynaneytce of Species — Difficulties in distinffuishing between Species and 

 Varieties, 



As the variations which have arisen among the Domestic animals, and especially in 

 the Dog, appear very considerable, it has been thought probable by many Naturalists 

 that our different races of Dogs have descended from several distinct species. In 

 this way the difficulties of explaining the causes of their variations are wholly avoided, 

 rather than resolved. It remains to be shown, under this view of the subject, from 

 how many species the domestic Dogs have descended. No Naturalist could propose 

 to establish a species for every distinct race, which are upwards of fifty in number. 

 Still less, as all these races are capable of forming crosses with each other, could they 

 institute a species for every combination in pairs ; nor could they extend it to those se- 

 condary and tertiary crosses which might be formed among their posterity, both with 

 each other and with the original races, thus rendering the number of species abso- 

 lutely infinite. It has been rather attempted to limit the sources of the several races 

 of Dogs to a small number, marked by important differences. Yet it becomes equally 

 impossible to point out the particular stocks from which these races have descended, 

 or the variations which must bo regarded as important, without falling under objec- 

 tions of another kind. 



There are several considerations which clearly establish the important fact that 

 Species have a real existence in Nature; — that certain forms have been assigned to 

 each animal from the origin of things ; and that although the animals are hable 

 to diverge from their primitive forms, they always possess a preservative tendency, a 

 nisjts fonnativits^ and are ever ready to revert to the original type when the external 

 causes of change are removed. The entire Animal Kingdom is divided into a num- 

 ber of distinct species, each of which perpetuates its own form, without ever trans- 

 gressing certain limits, or acmiiring the characters of another species. 



In all the varieties observed to arise among the Mammalia, the form of the bones 

 preserves a remarkable stability, which would not always be expected from the ap- 

 pearance of the external parts. The Baron Cuvier compared the skulls of Foxes 

 from the North of Europe and from Egypt with those of France and with each other 

 yet he found no other differences than such as might distinguish one individual from 

 another. The antlers of the Rein-Deer and Stags often vary in size, and the 

 same may happen with the tusks of the Elephant; but two individuals of any one of 

 these species, however dissimilar they may be in size, do not exhibit the slightest 

 difference in the number of their teeth, or the articulations of their smallest bones. 

 This is also observed with the domestic Cattle, which may be destitute of horns 

 or have them of variable length, and yet they possess an exact correspondence in all 

 the other parts of the skeleton. 



Thus the forms of the bones in general vary but little; while their modes of con- 

 nexion, their articulations, and the form of the great molar teeth, remain constantly 

 the same in each species. The divided Hoof of the Hog sometimes becomes consoli- 

 dated, and this may be regarded as the extreme limit of variation among the bones of 

 our domestic herbivorous animals. 



The variations of the bones in the different kinds of Dog have undergone a special 

 examination by M. Frederic Cuvier, performed at the request of his brother upon the 

 specimens at the Museum d'Histoire Naturelle. To enter fully into the details ot 

 this investigation would at present be out of place. It will suffice here to mention, 

 that a general correspondence in all the parts of their skeletons was found to exist, 

 and at the same time some important variations, especially in the degree of elevation 

 of the frontal sinuses. The teeth were always of the same number and general form ; 

 sometimes an additional false molar, or a tubercle, was observed on one side or on the 

 other. It is well known that all Dogs have five toes on the fore-feet, and only four 

 on the hinder, while there is a slight trace of a rudimcntil fifth toe in the hinder 

 metatarsal bone, which, however, shows no appearance on the outside. These toej 

 being of unequal length, usually preserve the same relations in all the races ; but 

 sometimes a fifth toe exhibits itself on the internal surface of the hinder-feet. It is, 

 however, generally very short and imperfect, and this last is the maximum of varia- 

 tion found in the skeletons of all the races of Dogs. 



It thus appears abundantly evident, that animals now possess certain characters 

 which remain permanent, and resist all modifications, whether arising from climate or 

 domestication, or from a natural tendency to run into connate varieties. 



Time, however, it has been said, may effect a perceptible modification in the entire 

 characters of species. Fossil remains, and other Geological monuments, appear to 

 show that millions of years have elapsed since the first species of animals inhabited 

 the earth, and it is asked, may they not have undergone many modifications during 

 the interval ? 



