OF THE HUMAN SKIN. 63 



quent scratching not only disagreeable, but pos- 

 itively injurious. The effect of the parasites in 

 the shaft of the hair and the hair-follicles is much 

 more deleterious, so far as the life and growth of 

 the hairs are concerned ; for these latter may in 

 consequence either drop out entirely, or become 

 brittle, dry, and easily broken and rubbed off, 

 those remaining being lighter in color, and not 

 so strong and healthy. Absolute loss of hair 

 from the whole surface of the cutaneous envelope 

 may be caused by vegetable parasites, or the en- 

 tire scalp rendered as smooth and free of them as 

 a billiard-ball. Of course this must not be con- 

 founded with baldness, the result of natural or 

 premature loss of the hair. Further than this, 

 the presence of vegetable growth in the epidermis 

 or hair-follicle produces an eruption of a peculiar 

 character, simulating some natural cutaneous dis- 

 eases, and causing, also, itching and consequent 

 scratching. The nails, when infested, become 

 brittle, dry, thickened, and crumbling. More- 

 over, masses of vegetable growth may lie half 

 imbedded in the skin, which, producing loss of 

 the hair, and being of a yellowish color, finally 

 give the cutaneous surface a most revolting appear- 



