. --. 



.' - ' . 



TIUCIIOLOGIA MAMMALIUM ; 



caloric; a very Icnv specific gravity; no contractibility, and is of gradual and periodical 

 decidence.* 



THE MOST IMPORTANT DIVISION OF PILE. Pile is divided into hair and wool. (See fig. 

 2.) Hair and wool differ, one from the other, as follows: 



1st. In shape, hair being either cylindrical, cylindroidal, oval or ovoid al, while wool 

 is eccentrically elliptical. 



2d. In uniformity of shape of the same filament, hair being generally the same shape 

 throughout the filament, while wool is less uniform in this particular. 



3d. In the formation of the cortex, the scales of which upon hair are less numerous, less 

 pointed, and more depressed, while those upon wool are more numerous, more pointed, 

 and less depressed. 



4th. In direction, hair being either straight, flowing, or curled, while wool is crisped 

 and frizzled, and sometimes spirally curled. (See Frontispiece.) 



* EXPLANATION OF TERMS. Every part of the above description will, in its turn, in the succeeding page?, become a subject 

 of discussion; wherefore, all that is here required, is to explain, briefly, some of the terms. 



" Filamentus," from (filamentum,} a fine slender thread; used synonymously with "fibre," (fibra;) but we prefer the 

 use of the word" filamentous, reserving the words fibre and fibril, (a small fibre,) for the description of the intermediate sub- 

 stance of the shaft. 



"Appendage." Something that, being less than the principal, is annexed or added to it. 



" Dermis." The cutaneous system is divided into an external, including the dcrmis and epidermis, and an internal or 

 mucous membrane. Pile belongs to the dermis, but sometimes penetrates to the adipose tissue. 



We have not made an extensive microscopic examination of the skin ; and will therefore content ourselves with giving the 

 description of it found in the books. 



It is represented as consisting of four principal portions, viz: 



1st. The epidermis, or cuticle, which forms the outermost layer. This is of membranous structure, and is devoid of vessels 

 and nerves, and of course insensible. It is pierced with minute oblique holes, for the passage of hairs, and for the orifices 

 of exhalent and absorbent vessels. The cuticle exfoliates, in the form of scales, from the head, and also from the body after 

 certain cutaneous diseases. 



2d. The rete mucosum, the appareil pigmental of Flourens, (see Anat. Gen'l. de la Peau, &c., p. 34,) of the colored race. 

 Some are of opinion that in the white race this is entirely wanting; others suppose it exists, but is of a red color. 



3d. The corpus papillare. It consists of a collection of small papilla;, formed by the extremities of nerves and vessels 

 passing the corium which is beneath. Flourens considers these papilUc as prolongations of the true skin, and not as a 

 separate layer. 



4th, and lastly, comes the derma, corium, cutis-vera, or true skin; in which, principally, pile is set. 



Beneath all these is the adipose tissue. 



" Mammalia." We confine pile to this, notwithstanding the teachings of some physiologists that it is extended to other 

 classes of animals, and even to vegetables. "Quadrupedia corpus pilosum." (Lin.) "The bodies of all quadruped animals 

 are covered with hair." (Goldsmith.) "Les inamiferes sont les scul animaux dont le corps est gouvert de poil." (Elem. de 

 Zoo. 232.,) &c. 



"Follicle," the sac, in which the button of the hair is generally found, is most commonly, but improperly, called the 

 "root," which tends to mislead by suggesting a too intimate relation to a plant. We call it the "Follicle." 



The word "follicle" is generally applied, in anatomy, to excretory organs; but there is nothing in its derivation or termi- 

 nology to prevent us from using it in the sense here notified. Follicle, from the Latin "folliculus," (which is a diminutive 

 of "follis," a bag, purse or script,) is a small bag, purse or script, only, without limiting the use to which it is applied; and 

 in Botany, where it has been introduced, means, "a seed vessel, husk, or cover. It is so used by the French, also, by whom 

 " follicle" is defined, in Botany, to be "1" envelope membraneuse, dans la quelle sont contenue les graines des plantes." We 

 therefore use the word follicle to designate the little sac in which the posterior termination of the shaft, with its button, is 

 contained, when the pile is perfect and has come to maturity. 



"Insensible." Possessing no feeling, yet not deprived of all the properties of life. 



