THE MAMMALIA— MAN AND BEASTS. 



nnder the epidermis, or outer skin of animaJ3. With Plants, this is owin^ to the 

 inert secretion of the green matter, or chromule, and its ceasing to colour the cuti- 

 cular tissues. In all species, softness and moisture are the results of this albinism or 

 whiteness. Its ultimate cause is the want of vital energy, arising either from the 

 prolonged absence of the influence of Light upon the organic structure, or from the 

 intensity of a long-continued cold. Its effects may be either absolute and total, or 

 merely partial and local, even among the white varieties of animals and plants. Its 

 general tendency is to effeminate all beings. 



Accidental albinism may arise from old age, or the want of a continued renewal of 

 this coloured layer, which communicates its hue to the Hair, Feathers, or Scales. 

 It may be even induced before old age by disease, or by the absence of the usual 

 supplies of nutriment, or, among animals, by the violence of f^ar or any sudden emo- 

 tion, which may serve to withdraw from the exterior of the body its secretions, and 

 render the skin pale, or the hair white. There is also an accidental albinism from 

 the mechanical injury of the mucous pigment, arising from the bruising or tearing of 

 the skin, and on these spots, white hair or feathers will arise in the place of coloured 

 appendages. 



An opposite state of deep blackness, or Melanism, when the surface is said to be 

 mclanose or black, arises from the superabundance of the mucous subcutaneous tissue 

 in animals and plants, in which carbon exudes towards the exterior. Such are Ne- 

 groes, and all black or dark-brown animals, lurid and venomous plants, as the Solanea?. 

 This state of the skin is well fitted for skies, resplendent with Light and Heat. It 

 is attended in individuals with dryness, rigidity, and shortness of stature. 



Excessive cold, combined with the absence of Light, serves to drive the nutritive 

 and repairing juices far from the skin. This kind of albinism is especially remarked 

 in animals inhabiting the highest mountains and the polar regions, where they become 

 white in winter and coloured in summer. The large species of the Porcupine exhi- 

 bit these alternate annulations of white and brown, which are due to the alternations 

 of summer and winter. A similar effect might be produced on live Sparrows, by pluck- 

 ing the feathers, and rubbing their naked bodies with Spirit-of-wine. The feathers 

 which then succeed remain white, because the alcohol prevents the secretion of the 

 colouring subcutaneous matter, in the same manner as an excessive cold. A corre- 

 sponding effect may be produced by similar means upon the Mammalia. 



The colours of animals are intimately connected with the latitude of the place as 

 well as with the changes of the seasons, and seem, in general, delicately sensible to 

 the external stirr.uli of Light and Heat. In Mammalia and Birds, we find that the 

 hotter regions of the globe, as well as the summer months, are favorable to deep 

 and bright colours. 



Sir John Leshe's experiments on colour, as affecting the radiation and absorp- 

 tion of Heat, afford the best explanation of the iinal causes of these changes. " The 

 rate at which bodies cool is greatly influenced by their colour. The surface which 

 reflects heat most readily suffers it to escape but slowly by radiation. Reflection 

 takes place most readily in objects of a white colour, and from such, consequently, 

 heat will radiate with difficulty. If we suppose two animals, the one black, and 

 the other white, placed in a higher temperature than that of their own body, 

 the heat will enter the one that is black \^ith the greatest rapidity, and elevate 

 its temperature considerably above the other. These differences are observable in 

 wearing black and light coloured clothes during a hot day. When, on the other 

 hand, these animals are placed in a situation, the temperature of which is consider- 

 jibly lower than their own, the black animal will give out its heat by radiation to 

 every surrounding object colder than itst^lf, and speedily have its temperature reduced; 

 while the white animal will pait with its heat by radiation at a much slower rate. The 

 change of colour in the dress of animals is therefore suited to regulate their tempera- 

 ture by the radiation or absorption of caloric. While it is requisite that the tem- 

 perature of some species should be preserved as equally as possible, the coohng effects 

 of winter are likewise resisted by an additional quantity of heat being generated in 

 the system. An increase in the quantity of clothing takes place, to prevent that 

 heat being dissipated by communication with the cold objects around, and the dress 

 changes to a white colour to prevent its loss by radiation. In summer, the perni- 

 cious increase of temperature is prevented by a diminished secretion of heat, or the 

 secretion of cold, increased perspiration, the casihig of a portion of the winter cover- 

 ing, and by a superior intensity of colour in the remainder giving it a greater radiat- 

 ing power. The last character would, in the sunshine, by absorbing heat, prove a 

 source of great inconvenience, were its effects not counterbalanced by other arrano-e- 

 ments, and by the opportunity of frequenting the refreshing shade, or bathin"- in the 

 stream." Animals become light or gray in old age, and thus the too great dissipa- 

 tion of heat in their systems is prevented. 



If it were possible for any one to doubt the fact that the functions of animals and 

 plants correspond with the movements of the terrestrial globe, he would find a 

 convincing proof in the influence of the seasons, upon the casting of hair amon" the 

 Mammalia, the moulting of Birds, the changes of skin among the lower animals, and 

 the defoliation of Plants. 



In the Spring, all Nature is living and vegetating, expanding and developinn- its 

 productions ; the earth is clothed with verdure, the animals ai-e dressed in their 

 nuptial garbs, and their amours commence. The cause of this external expansion of 

 all beings originates in the circumstance that their functions, long oppressed by the 

 cold of winter, have acquired a superabundance of juices, sap, and nourishment 

 which only await the favorable moment of external heat to expand. Theii* f^erms are 

 developed with extreme vigour. In the human race, there is at this season a deter- 

 mination towards the skin, eruptive maladies become more prevalent, and exanthemata 

 sometimes appear as though budding were not exclusively confined to the venetable 

 kingdom. The Hair, Feathers, Horns, Scales, and Epidermis of animals, as well as 

 the Leaves, Flowers, and Fruit of vegetables, which have grown and expanded dur- 

 ing the Spring, assume their most glittering hues, if not during Summer, at least 

 during the six months of the year, when in our climate the sun is most above the 

 horizon. But at the approach of the autumnal equinox, living bodies, whether 

 Animals or Plants, are exhausted by the excessive action of their vital forces during 

 summer, and their functions become less vigorous, in proportion as Light and Heat 



diminish with the enfeebled rays of the Sun. Those external parts, prnt-'uced in tha 

 preceding Spring, cease to receive nutriment from the body; they have further 

 arrived at the full period of their growth, and arc incapable of receiving any more. 

 Hence they dry up or fade away; others become detached and fall. Sooner or later 

 at this season, we invariably witness the casting of hair, feathers, scales, horns, and epi- 

 dermis, as well as the dropping of flowers, leaves, and fruit, when each Living Being 

 enters into a kind of autumnal concentration preparatory to the ri"-our of winter. 



In the southern hemisphere, our winter being then its summer, and reciprocally, 

 the periods of casting or moulting are in each year opposite to ours. 



In the Torrid Zone, the Sun passes twice a year from the one tropic to the other, 

 so that it produces, to a certain extent, two winters and two summers. The winter 

 is there the season of continual rains ; it also determines twice a year the castin" or 

 moulting period of animals and plants, and doubles the number of the ruttin^^ seasons. 

 From these circumstances, it arises that Living Beings experience a two-fold waste 

 of vital force, and live in these warmer regions at a faster rate than elsewhere. They 

 are continually producing or wasting; new flowers spring up next to the fruit ; new 

 leaves replace the old and faded; the Bird prepares its nest of eggs, and sin<'s new 

 carols within the hearing of its brood of six months old ; and the Quadrupeds con- 

 sume in a continual state of generation, gestation, and lactation. 



In colder countries, and on the summits of elevated mountains, there exists another 

 kind of change in tho feathers of Birds and the hair of Mammalia, which arrives at 

 the period of winter. The white robe, the symbol of chastity and sexual indifference, 

 is particularly fitted to these cold regions, in the same manner as the brilliant robe 

 of summer is in correspondence with the full vigour and activity of the reproductive 

 system. Thus the Hare of tho Alps {Leptis variabilis) and the Ermine, as well as 

 a great number of other IMammalia, with an immense multitude of Birds of the 

 Northern P.egions, especially the Waders (GraUce) and M'eb-footed Birds (Palmi- 

 pedes)t which are covered in the summer season with hair or feathers of brown and 

 more brilliant hues, acquire a pale gray or uniform white during the winter. 



It has been considered by some, that the white garb of arctic animals serves to 

 protect them from their enemies, by assimilating their colour with that of the snow. 

 But Nature, pursuing a fair system of reciprocity, imparts the same colour to the 

 beasts and birds of prey, so that, in reality, this provision is less effectual than has 

 been commonly supposed. 



Dr Fleming has made the following observations on the cause of the chancre of 

 colour in those quadrupeds, which, like the Alpine Hare and Ermine, become white 

 in winter : — " It has been commonly supposed that these Mammalia cast their hair 

 twice in the course of the year; at harvest, when they part with their summer dress 

 and in spring, when they throw off their winter fur. This opinion, however, does 

 not appear to be supported by any direct observations, nor is it countenanced by ana- 

 logical reasoning. If we attend to the mode in which the human hair becomes "ray 

 as we advance In years, it will not be diiScult to perceive that the chan'^e is not pro- 

 duced by the growth of new hair of a white colour, but by a change in the colour of 

 the old hair. Hence there will be found some hairs pale towards the middle and 

 white towards the extremity, while tho base is of a dark colour. Now, in ordinary 

 cases, the hair of the human head, unlike that of several of the inferior animals ii 

 always dark at the base, and still continues so during the change to gray ; hence we 

 are disposed to conclude from analogy, that tho change of colour, in those anlmaU 

 which become white in winter, is effected, not by a renewal of the hair, but by 3. 

 change in the colour of the secretions of the rete-mucosum, by which the hair is 

 nourished, or perhaps by that secretion of the colouring matter being diminished or 

 totally suspended." An Ermine shot by Dr Fleming in May 1 814, in a -^arb inter- 

 mediate to its summer and winter dress, confirmed this view of the subject. In all 

 the under parts of its body, the white colour had nearly disappeared, in eschan'^e for 

 the primrose-yellow, the ordinary tinge of these parts in summer. The upper parts 

 had not fully acquired their ordinary summer colour, which is a deep yellowish-brown. 

 There were still several white spots, and not a few with a tinge of yellow. Upon 

 examining those white and yellow spots, not a trace of interspersed new short brown 

 hair could be discerned. This would certainly not have been the case if the chan'^e 

 of colour is effected by a change of fur. Besides, while some parts of the fur on the 

 back had acquired their proper colour, even in those parts numerous hairs could be 

 observed of a wax-yellow, and in all the Intermediate stages from yellowish-brown, 

 through yellow to white. These observations leave little room to doubt that the 

 change of colour takes place in the old hair, and that the change from white to brown 

 passes through yellow. If this conclusion be not admitted, then we must suppose that 

 this animal casts its hair at least seven times in the year. In spring it must product: 

 primrose-yellow hair, then hair of a wax-yellow, and lastly of a yellowish-brown. 

 The same process must be gone through in autumn, only reversed, and with the ad- 

 dition of a suit of white. The absurdity of this supposition is too apparent to be 

 further exposed. Thus the hair, as long as it remains connected with the body, 

 participates in the general life of the system, and is influenced in respect to its colour 

 by the secretions of the raucous net-work of the skin. 



There exists a general tendency in all living bodies to develop themselves 

 from within, outwards. This evolution of living bodies is the ultimate cause of thoso 

 changes which the external surface of their bodies undergoes during the several i)c- 

 riods of their existence, and determines the variations in the quantity of their cloth- 

 ing : the proximate causes of change are the external stimuli of light and heat. As 

 each appendage of the animal body Is endowed with a vital power peculiar to itself, it 

 must have Its pccuhar periods of youth, perfection, decay, and death. When any 

 organic portion of the body is completely dead, it separates and falls, because a living 

 substance cannot co-exist with a dead one. The casting of hair, and all other kindi 

 of moulting or external change, is nothing more than the natural death of a certain 

 portion of an animal body, in consequence of the development of other parts interior 

 to it, and this kind of function is regulated by fixed laws. 



The external parts of animals and plants which are renewed each year arc of two 

 kinds. They may have a peculiar organic conformation, as we find in hair, horns, 

 teeth, leathers, and leaves, or they may have a simple structure, scaly or foliaceous, 

 as we liud in the epidermis or outer skin, shells, and membranes. 



