56 VEGETABLE PAKASITES 



minate in the scarf-skin of the human body, in 

 the nails, in the little follicles from which the hairs 

 grow, and in the root and shaft of the hair itself; 

 and that their presence produces partial destruc- 

 tion or total loss of the hair or nails, and on the 

 skin certain morbid appearances which have been 

 classified among cutaneous diseases. 



We shall confine ourselves to those which thus 

 give rise to diseases of the skin, for there are many 

 more vegetable growths that infest the mucous 

 membrane and internal portions of the body. A 

 knowledge of the presence of these vegetable or- 

 ganisms in certain cutaneous affections, and their 

 being the cause of them, does not date back be- 

 yond 1840, when the microscope had commenced 

 to reach a degree of development which rendered 

 its use constant not only in anatomy, but als© in 

 clinical medicine. From that time to the present, 

 scientific physicians and surgeons have steadily 

 and constantly been sweeping the fields of their 

 microscopes as the astronomers ' have swept the 

 starry field with their telescopes, and thus from the 

 efforts and studies of a large number of trained, in- 

 telligent, and laborious observers, the atoms of light 

 in the heavens, and the atoms of animal and veg- 



