THE AMERICAN NATURALIST [Vol. LIV 



tal from the proximal end of some one hair shaft. This 

 can be done under the microscope, remembering: first 

 that the image is reversed, and second, that the free 

 edges of the cuticular scales lie always at the ectal, or 

 distal portion of the scale, and so indicate the direction 

 of the distal extremity of the hair. A much more simple 

 method is to rub the hair in question between the thumb 

 and finger, when it will always travel in the direction of 

 the bulb, i.e., in the direction of its proximal extremity. 

 This fact that the free ectal edges of the cuticular scales 

 develop in such a way that they are always directed out- 

 ward from the animal, suggests that they may afford pro- 

 tection against the intrusion between the hairs, and so 

 on to the skin itself, of foreign bodies, parasites, and 

 water. Furthermore any such extraneous elements 

 which may have gained entrance, apparently would tend 

 to be worked outward away from the skin' to the outer 

 surface of the hair covering by the motions into which 

 the hair is thrown by the movement of the muscles of the 

 body during locomotion. 



In preparing a series of animal hairs to be used as 

 type specimens for determinative comparisons with un- 

 known hairs it is well to have a series of slides prepared 

 to show the medulla (mounted in balsam as previously 

 directed), and another series of slides with the hairs 

 mounted thereupon in dry cells" (washed in the ether- 

 alcohol, and stained or not as each requires), to show 7 the 

 cuticular scales. Since this later method of preparing 

 hairs seems to be attained with little success (too much 

 dust gathering upon the hair, the fibers obscuring the 

 sculpturings of the cuticular scales), it is better, per- 

 haps, to keep a tuft of each species of hair in a small phial 

 or double envelope, and make fresh preparations when 

 necessary. Both the balsam-mounted slides ami the un- 

 treated hair samples should be filed away following the 

 i-lassilieat ion scheme for the scales and medulla given 

 in this paper. This facilitates the immediate selection 

 of the particular group of hairs possessing the charac- 



