MICROSCOPIC OBJECTS. 43 



assumes a bright orange colour. The use of this aug- 

 mentation in bulk towards the end is not ascertained; 

 but Mr. Pritchard remarks that " a similar structure on 

 a large scale may be observed in the small feathers from 

 the breast of the Indian Humming-bird, which latter 

 afford interesting microscopic objects under moderate 

 amplification." 



Hair of the Larva of the Dermestes. — ^This curious hair, 

 as also those of the mouse, bat, &c., will be found de- 

 scribed in the chapter on Test Objects. 



Human Hair. — -In the adult, the friction of the hairs 

 against each other is such that their external structure is 

 seen with difficulty. That the hair is imbricated any 

 person may be convinced by rubbing a single one between 

 the fingers, first in one direction and. then in the other, 

 when the resistance offered in drawing it backwards- 

 (that is, from the points to the root) may be readily felt. 

 This affords a curious example of the dehcacy of tactile 

 feehng over sight. "From a consideration of this circum- 

 stance, and finding the hairs of infants frequently matted 

 or felted together in small knots, after washing, arising 

 from their jagged surfaces," Mr. Pritchard "was induced 

 to examine the latter, and finding the asperities much 

 more decided than in that fi'om the adult, procured a 

 specimen from a babe only two hours old", in which the 

 imbricated structure was very distinct." In specimens of 

 this hair mounted in Canada balsam the exterior charac- 

 ters are obliterated. 



Hair of Caterpillars. — The hairs of some species when 



