Fungi Vrohahhi Pathogenic 3 13 



cases and attributed liis Failure in the remainder to a considerable con- 

 comitant growth of common air-borne fungi. It was possible to inoculate 

 other mediums successfully from a vigorous primary growth. Benham, 

 Emmons and others have also been occasionally successful in obtaining a 

 cultural growth of P. ovale. 



In a report on the possible role of P. ovale as the cause of seborrheic 

 dermatitis, Moore, Kile, Engman and Engman found that inoculation of the 

 cultures of an organism which they believed to be P. ovale in human sub- 

 jects and in animals frequently resulted in the development of a "dermatitis 

 of erythema or brown scaliness," the histologic- picture of which resembled 

 that of seborrheic eczema. They stated that the reproduction of a derma- 

 titis, as reported by MacLeod and Dowling, was the most convincing evi- 

 dence in favor of the etiologic importance of a microbe. In a prior report 

 Moore expressed doubt that the organism isolated by MacLeod and Dow- 

 ling was P. ovale. It seems, therefore, that rigid control tests both as to 

 subjects and as to the inoculated material are essential in order to deter- 

 mine pathogenicity by inoculation experiments. Moore, Kile, Engman and 

 Engman reported that cutaneous tests on 18 patients with different extracts 

 prepared from the cultural growth of P. ovale resulted in a number of 

 positive reactions. These reactions were manifested by the development of 

 an area of erythema at the site of injection, and in a few instances a scaly 

 red dermatitis appeared. No mention was made of control tests. In a sec- 

 ond and more complete study, Kile and Engman inoculated P. ovale and 

 produced a scaly condition on human scalps from which P. ovale was again 

 recovered. Control tests with two other fungi failed to produce comparable 

 inoculation results. 



In a survey of the scalps of 100 patients, MacKee, Lewis, Spence and 

 Hopper made an arbitrary clinical differentiation into five groups based 

 on clinical features common to each group. Pityrosporum ovale was fre- 

 quently noted in all groups, being present on 70 per cent of normal scalps 

 and on 66 per cent of the scalps on which there was a concomitant skin 

 disease. In the majority of examinations, it was found that the concentration 

 of the organism was higher on scalps with dandruff than on normal scalps. 

 In a second series of patients it was noted that P. ovale was also a common 

 inhabitant of the skin, more frequently found in scrapings from the surface 

 of the nose than in material manually expressed from the nose. There is 

 still divided opinion among investigators regarding the pathogenicity of 

 P. ovale. Many feel that the work of Engman and his collaborators is de- 

 cisive and that there is as much, if not more, proof of a causal relationship 

 between P. ovale and dandruff as between M. furfur and tinea versicolor. 



(a) Microscopic features.— In a search for the micro-organism the chief 



