400 PHALEN AND NICHOLS. 



Clinically it seems as if the milder forms did not develop into the 

 more severe. This can only be decided by further observation, especially 

 of cultures obtained. 



The diagnosis depends on rinding blastomycetes in the lesions con- 

 stantly and in such number that they can not be regarded as accidental. 

 Control examinations of scales, crusts and pus from other lesions have 

 shown occasional blastomycetes, but these are not constantly present nor 

 in such numbers as are seen in the lesions described. Of course, sections 

 and cultures are desirable, but in our experience the latter are difficult to 

 obtain and are unnecessary before starting treatment. After seeing a 

 number -of cases we have been able to pick out others from their clinical 

 appearance. In the milder forms the presence of blastomycetes and 

 absence of any fungi in a manifestly parasitic disease differentiate the 

 affection from ring-worm, Tinea imbricata, etc. The severe forms may 

 be taken for tuberculosis or syphilis. If tuberculous they will not heal 

 up in one to two months of treatment with piotassium iodide. The 

 history and clinical appearance differentiate the affection from syphilis, 

 as in the latter disease there is no such overgrowth of the epithelial 

 structures. In tertiary yaws the lesions are ulcerative, while in this 

 form of blastomycosis of the skin no definite ulcerations have been seen. 



IV. ORGANISM AND CULTURES. 



We have been unable morphologically to distinguish any difference in 

 the organisms from the various cases. If a scale is taken from type A, 

 or a crust or some pus from either B or C and macerated thoroughly in 

 a ten to twenty per cent solution of potassium hydroxide, the organisms 

 become very distinct. Their most striking feature is a double contour, 

 usually less than 1 ^ thick, but occasionally • some are seen in which it 

 is 2 /a. There is a great variety of forms; the most frequent is the 

 round, measuring 5 to 10 /*; man}' minute ones of the same kind are 

 seen, 2 to 3 /j, in diameter, often in clusters; budding forms are frequent 

 and others making a figure of 8. Another frequent appearance is -the 

 rod-like one with rounded ends. Some forms are elongated and in 

 phantastic shapes. These organisms stain with difficulty, a faint rim of 

 blue being often all that can be seen with the modified Gram's stain. 

 No internal structures have been made out, nor is any evidence of 

 sporulation seen except in cultures. 



In sections the organisms are found in small numbers in the types 

 A and B, in the more superficial layers of epithelium between the cells. 

 We have found no differential stain for them. With hematoxylin and 

 eosin they stain to a light brown and often have a halo about them. 

 They are most readily demonstrated (fig. 10) in unstained sections 

 treated with potassium hydroxide and mounted in glycerin. The double 



