OR, A TREATISE ON PILE. 21 



Shaft, color underneath the sheath, white; from the sheath for i 8 ths of an inch, black; 

 for T %ths, white; slightly colored for ^th; then white for T ^ths; and dark brown 1 inch 

 to the apex; the inferior termination quill shaped, surface squamose, perforated; no button. 



Sheath length, T |_ ; diameter, ^ 3 of an inch ; color, dark brown ; easily removed from 

 the shaft with the fingers, after a slight maceration. 



Disks one cut from beneath the sheath has, 1st, a fibrous cortex; 2d, a large, black, 

 solid substance; 3d, a small white circle, or ring; 4th, a perforation in the centre. Another 

 disk, cut from the black portion above described, has, 1st, a white fibrous cortex; 2d, a 

 solid black substance; and 3d, a centre of solid white. In cutting this disk, a white fibre 

 of the cortex is left pendant. A disk from the white shows, 1st, a white substance; 2d, a 

 centre whitish. A fourth cut from the portion which was slightly colored, shows, 1st, a 

 white substance; 2d, a dark cloudy substance; 3d, a perforated white centre. 



Apex pointed, sometimes furcated. 



Inferences. The substance of the cortex is fibrous, but it may have a squamose 

 exterior; the coloring matter is disseminated in the cortex and intermediate substance. 

 The central canal is sometimes void, and sometimes filled with a white substance. 



Note. These whiskers were drawn out of a dried specimen, which accounts for our 

 having no follicle to examine and seeing no vessels, they being left behind. 



OF THE WHISKERS OF THE POSSUM. (Didelphis virginica.) Sepecimen, the common 

 Possum, found wild near Philadelphia. 



Length, from 2 T ^ to 3 inches; diameter, ^ of an inch. Stalk, cylindrical, gradually 

 tapering to a point, unless, (which often happens,) it is furcated. Direction, undulated; 

 posterior extremity perforated; no button. Incurs, (which is a dried specimen,) blood- 

 red central grains. Disks, one exhibited a light cortex, a white substance, a compressed 

 dark-colored ring, and a central canal. Another shows a white cortex, a dotted substance, 

 a compressed dark ring, and a central canal. (See fig. 13, a and b, for a representation 

 of the stalk 13, c and d, for the disks.) 



Remarks on Whiskers. The differences between whiskers and common hairs are: 1st. 

 An ordinary hair has a button, but a whisker has none. 2d. The posterior extremity of 

 a whisker is perforated, that of a hair is not. 3d. The lower extremity of the shaft of a 

 whisker is sometimes colored blood-red, which is not the case with that of an ordinary 

 hair. 4th. There is a great ductility and tenacity in a whisker, compared with an 

 ordinary hair. 5th. The vessels of a whisker are more apparent than in an ordinary hair. 

 6th. The cubic or cuneiform white matter, seen in the canal of a whisker, has not been 

 detected in ordinary hairs. 



OF BRISTLES. The word is from the Saxon "bristl," and means the strong, stiff hairs 

 that are found upon the back of the boar. 



Cuvier says they are chamfered* their whole length, by 20 or more furrows, formed 



* Chamfer is from the French " ehambrcr," a furrow or hollow in a column. 



