126 



VIEWS OF THE MICROSCOPIC WORLD. 



and 205, vary in form and size, their diameters ranging from one-two thousandth 

 to one-three hundredth* of an inch. The chief van- 

 Fig. 204. Fig. 205. eties are here exhibited of their relative sizes in figures 

 204 a and 6, and 205 a, and are delineated as they 

 are seen by transmitted light ; the real diameter of 

 the hair in cut 204 a, is only the sixteen hundredth part 

 of an inch. When the hairs are viewed by reflected 

 light, their appearance is changed, for the solid parts 

 then reflect more light than the transparent, and appear 

 white, while the transparent portions are comparatively 

 dark. The appearance presented by a magnified hair 

 when viewed by reflected light is shown in figure 205 

 b. The hair of the bat is different from that of the mouse, and consists of many 

 varieties distinguished from each other in form and structure. The two prin- 

 cipal kinds are delineated in figures 206 and 207. The first represents a collection 



Fig. 206. 



207. 209. 208. 



of hairs scattered promiscuously together, each possessing a figure like that which 

 would be formed by a series of cones with the points of each inserted into the 

 middle of the base of another. The second exhibits a curious spiral struc- 

 ture. Figure 208 is a white hair from a young cat; figure 209 that of 

 a Siberian fox, and 210, the hair of a common caterpillar, which divides into 



Fig. 210. 



branches ; but the form of these hairs is different for every species of caterpillar ; 

 in some they resemble the spreading plumes of the peacock's tail, while 

 others are adorned with delicate tufts of hair, and bristle with thorns. 



