i62 INFECTIOUS AND PARASITIC DISEASES. 



In local affections of the skin, the agents 

 Local in the following diseases are cast off: 



Diseases Cutaneous actinomycosis, blastomycetes, 

 OF THE Skin, ring-worm of various parts of the body, 



tinea sycosis (barber's itch), favus, tinea 

 versicolor, impetigo contagiosa, furunculi (boils), malig- 

 nant pustule (local anthrax), erysipelas, pinto (spotted 

 sickness), mycetoma (Madura foot), lupus vulgaris 

 (cutaneous tuberculosis), syphilis, leprosy, yaws, glan- 

 ders (farcy), etc. 



Animal parasites are found in these affec- 

 Parasites tions of the skin: Scabies, pediculosis 

 OF Skin. (pubis, capitis, vestimentorum), Craw-craw, 



and Guinea-worm disease (Dracunculus 

 medinensis). The larvae of the common house-fly are 

 sometimes found in wounds, and the grubs or larvae of 

 special flies (bot-fly, gad-fly, etc.), in tropical and sub- 

 tropical countries, quite frequently take up their abode 

 beneath the skin. 



The blood as an avenue of exit for infec- 

 Blood. tious agents was a sterile field for research 



until the relationship of a biting insect to a 

 disease was established by the discovery, in 1893, by 

 Theobald Smith, that a tick is the intermediate host for 

 the micro-organism of Texas cattle fever. Long before 

 this discovery physicians had suspected that mosquitoes 

 played a role in both malaria and yellow fever — but 

 the proofs were lacking in both diseases. These have 



