418 HIGHER HYPHOMYCETES AS THE CAUSE OF DISEASE 



experimentally by keeping them for a short time in a closed space 

 where the air contains spores of this mould. Other moulds which 

 have occasionally been found as the cause of pneumonomycosis and 

 other internal affections are Aspergillm flavus, niger, and subfucus; 

 Mucor rhizopodiformis . and corymbifer. All of these when injected 

 intravenously into rabbits in an emulsion containing numerous spores, 

 produce multiple mycotic foci in the internal organs from which the 

 animals die. Natural infection with them are, however, rare. 



DERMATOMYCOSES. 



A variety of diseases of the skin due to hyphomycetes or moulds 

 occur in man and the domestic animals. The most important of the 

 microorganisms which cause such affections, known under the 

 collective name of dermato mycoses, are the following: 



Trichophyton Tonsurans. This mould is the cause of the skin 

 disease known as herpes tonsurans, characterized by the formation 

 of scales and the falling out of the hair. It has been found associated 

 with this affection in man, the horse, dog, cat, goat, sheep, and hog. 

 It was discovered by Gruby (1842) and Malmsten (1846). 



METHOD OF EXAMINATION. In order to examine this and other 

 moulds causing various dermatomycoses, some scales with attached 

 hairs must be removed from the skin by scraping with a scalpel. 

 The material is then best placed in a test-tube and well shaken for 

 some time with chloroform, in order to extract the fat. After this has 

 been accomplished, the chloroform is poured off and its last remnants 

 are allowed to evaporate from the scales and hairs. The latter are 

 then placed on a slide soaked in a 33^ per cent, solution of caustic 

 soda or potash, covered with a cover-glass and examined in this fluid 

 under a higher power dry lens of the microscope. The scales and 

 hairs are immersed in the strong alkaline solution in order to make 

 them transparent so that the filaments and the spores of the mould 

 may become readily visible. They are then seen surrounding the 

 hair as a septate mycelium and as rows of highly refractive round 

 bodies which are the spores. So many of the latter are usually present 

 that it is often impossible to detect the filaments; they can, however, 

 generally be more easily seen in the scales than in the hairs. The 

 spores, as a rule, measure 4 to 6 micra in diameter, but they may vary 

 between 2 to 8 micra. The hyphen or filaments are about 4 micra 

 thick. Pure cultures are difficult to obtain, since the hair and scales 

 of skin also contain numerous bacteria. Sabouraud has succeeded 

 in getting a growth of the Trichophyton tonsurans in a beerwort 

 medium composed of maltose 4 parts, peptone 2 parts, tinctura fucus 

 crispa 1.5 parts, and water to make 100 parts. Krai's method consists 

 in rubbing up the hairs with sterile silicon powder and inoculating it 

 in gelatin tubes, from which plates are poured. Kitt succeeded in 



