124 ON THE BONES, &c. OF THE ANIMAL FRAME. 



"born white, or nearly so ; and that the black pigment which colours them is 

 not fully secreted till several months after birth. It sometimes happens, 

 though rarely, that from a morbid state of the secretory organs there is no 

 pigment s'ecreted at all, or a white pigment is secerned instead of a black. ; 

 whence we have white negroes, or persons exhibiting all the common cha 

 racters of the negro-breed in the form of the head and features of the face, 

 with the anomaly of a white skin. And it sometimes happens, though still 

 more rarely, that from a similar kind of morbid action affecting the secretory 

 organs, the black 'pigment is secreted in alternate or interrupted divisions ; 

 and in this case we have negro children with brindled, marbled, or spotted 

 skins : an instance of which was brought to me by a gentleman about two 

 years ago, who had purchased the child in America, and who, I believe, after- 

 ward exhibited it in this metropolis as a public show. 



The CUTICLE is the thinnest of the layers that form the general integument 

 of the skin. It often, however, becomes thicker, and sometimes even horny, 

 by use. Thus it is always thicker in the sole of the foot and palm of the hand ; 

 and horny in the palms of blacksmiths and dyers ; arid still more so in the 

 soles of those who walk barefooted on burning sands. It is annually thrown 

 off whole by many tribes of animals as grasshoppers, serpents, and spiders 

 and as regularly renewed ; and by some animals it is renewed still more 

 frequently : it is shed not less than seven times by the caterpillar of the moth 

 and butterfly before either becomes a chrysalis. There are a few plants that 

 exfoliate their cuticle in the same manner, and as regularly renew it. The 

 West India plane-tree throws it off annually. 



From the cuticle shoots forth a variety of substances, which either protect 

 or adorn it, the roots of which are not unfrequently imbedded in the true skin 

 itself. Of the harder kind, and which serve chiefly as a defence, are the 

 nails, scales, claws, and horns ; of the softer and more ornamental kinds, are 

 hair, wool, silk, an,d feathers. 



HAIR is the most common production, for we meet with it not only in all 

 mammals, but occasionally in birds, fishes, and insects, varying in consis- 

 tency and fineness, from a down invisible to the naked eye, to a bristle strong 

 enough to support, when a foot long, ten or twelve pounds weight without 

 breaking. 



WOOL is not essentially different in its chemical properties from hair, and 

 it varies equally in the fineness and coarseness of its texture. It is generally 

 supposed by the growers, that the fineness of its texture depends upon the 

 nature of the soil ; yet of the two finest sorts we are at present acquainted 

 with, that of Spain and that of New South Wales, which last is an offset 

 from the Cape of Good Hope, and has yielded specimens of broad cloth, 

 manufactured in this country, as soft and silky as that of unmixed Merino 

 wool that of Spain is grown on a pure limestone soil, covered with small 

 leguminous plants instead of with grass ; and that of New South Wales on a 

 soil totally destitute of lime, and covered with a long, rich, succulent grass 

 alone. 



Food, however, or clinaate, or both, must be allowed, under certain circum- 

 stances, to possess a considerable degree of influence ; for it is a curious fact, 

 that the hair of the goat and rabbit tribes, and the wool of the sheep tribe, are 

 equally converted into silk by a residence of these animals in that district of 

 Asia Minor which is called Angora, though we do not know that a similar 

 change is produced by a residence in any other region; while, on the con- 

 trary, the wool of sheep is transformed into hair on the coast of Guinea. 



The fine glossy SILK of the Angora goat is well known in this country, as 

 being often employed for muffs and other articles of dress. How far these 

 animals might be made to perpetuate this peculiar habit by a removal from 

 Angora to other countries has never yet been tried. Upon the whole, the 

 soil and climate of New-Holland offer the fairest prospect of success to such 

 an attempt ; and under this impression I have for some time been engaged in 

 an endeavour to export a few of each genus of these animals from Angora to 

 Port Tackson. 



