242 THE MICROSCOPIST. 



calculus. Some regard it as indicating a strumous and 

 ill-nourished system. 



V. LIST OF PARASITES INFECTING THE HUMAN BODY. 



I. Epiphytes, or vegetable parasites. Parasitic lesions 

 of the surface are denoted by the infiltration or destruc- 

 tion of hairs and epithelial textures by the sporules of a 

 fungus, which by union or growth form elongated branches 

 or mycelia. Reference has been made, page 136, to poly- 

 morphism, or the varieties of form produced by the same 

 fungus germ, so that the names ascribed to these parasites 

 must be regarded as only provisional. The diagnosis of 

 fungi on the skin, hair, or epithelium requires care and 

 skill in microscopic manipulation, and the use of liquor 

 potassse long enough to render the specimen transparent. 



1. The Trichopkyton tonsurans, present in ring-worm of 

 the body, scalp, or beard. Its anatomical seat is the 

 interior of the roots of the hairs, but it also covers the 

 epidermis between the hairs, and invests them in a white 

 sheath, producing inflammation of the follicles and sur- 

 rounding tissues, and subsequent baldness. 



2. The Trichophyton sporuloides, present in the disease 

 called plica polonica. 



3. Achorion Sckonleinii and the Pacciniafavi, present in 

 the honeycomb ring-worm. 



4. Microsporon mentagraphyta, present in the Mentagra. 



5. Microsporon furfur, the cause of liver-colored spots, 

 or Pityriasis versicolor. 



6. Microsporon Audouini, occurring in Porrigo decal- 

 vans$ or bald patches. 



7. Mycetoma Carteri, the cause of the " fungous foot of 

 India/' 



8. Oidium albicans, in diphtheria and aphtha. 



9. Cryptococcus (or Torula) cerevisice, yeast plant in blad- 

 der or stomach. 



