59 



Having stated thus much on the growth of hair, I shall proceed at 

 once to the examination of that of the bat tribe : of sixteen species 

 of these animals, the hairs of which I have examined, all were analo- 

 gous in structure to one or other of the forms represented in Plate 7, 

 figs. 7, 8, 9, 10, &c. They are characterized by the shaft presenting at 

 intervals peculiar raised markings, which are arranged sometimes trans- 

 versely, at others obliquely, to the axis of the hair ; in some specimens 

 they project a considerable distance from the general surface, and 

 the true shaft of the hair appears between them at certain intervals. 

 Having on more than one occasion failed in pulling the hairs out of 

 the skin with my fingers, in order to obtain some a knife was used, 

 and the hair held firmly between its edge and the thumb : on exami- 

 nation of these hairs afterwards it was found that they were altered in 

 character, the markings on them, which were so peculiar, being de- 

 stroyed in some parts and left undisturbed in others ; they appeared as 

 if something had been taken away from them in certain points. This 

 led me to expect that the curious surfaces which these hairs present 

 might be owing to a development of scales on their exterior, and re- 

 peated examination has convinced me of the truth of this supposition. 

 I have since found that by submitting hair to a scraping process, 

 minute scale-like bodies, tolerably constant as far as regards their 

 size and figure, can be procured, so that bat's hair may be said to 

 consist of a shaft invested with scales, which are developed to a 

 greater or less degree, and vary in the mode of their arrangement in 

 the different species of the animal. The surface of that part of 

 the hair nearest the bulb is nearly free from any trace of scale, (fig. 7, a) 

 but as we proceed towards the apex the scaly character becomes 

 more evident. In many hairs the scales lie in a direction at right an- 

 gles with the shaft, and one scale forms a complete band around the 

 shaft ( fig. 6 ) ; in others they run with varying degrees of obliquity, 

 giving a true spiral character to the hair ( fig. 9 ) ; whilst in many 

 others scales may be seen in all stages of development (fig. 10). 

 The larger kind of hairs, such as are procured from the various spe- 

 cies of vampire, are generally of a dark yellow colour, and are com- 

 paratively smooth externally, but exhibit a cellular structure internally. 

 The scales may be readily procured for examination by scraping the 

 hair, whilst still adherent to the skin, with a knife, in a direction from 

 the apex towards the bulb ; or, when separate, by laying them on the 

 glass on which they are to be mounted, keeping them steady either 

 with the finger or another piece of glass, and passing a knife along 

 them. A more simple plan still may be had recourse to, which is 



