290 YEASTS AND YEAST-LIKE FUNGI 



all of them. If this observation can be confirmed, it would seem 

 that the generic term Mycoderma must be dropped in favor of the 

 genera described on the basis of their perfect stages, Mycoderma 

 species are found in the same habitats as the perfect film-forming 

 yeasts, as sherry and certain Arbois wines and various pickle brines, 

 and seem to be of equal or greater importance. There is a large 

 literature on these organisms, much of which is confused and con- 

 tradictory. Classification of species has not been satisfactory and 

 the genus (if it is a genus) needs thorough study. Lodder ^* has 

 made an excellent start but she has so far treated only cultures of 

 which were available to her and strains with poorly developed or no 

 mycelium. Whether the many strains of asporogenous film-forming 

 yeasts with better developed pseudomycelium should be placed in 

 separate genera or combined with Mycoderma will be clearer when 

 more work is done. A monographic treatment of the genus is to be 

 hoped for. 



Pityrosporon. Pityrosporon is a very small yeast which grows on 

 the skin, being particularly abundant in scalps in which there is an 

 abundance of oily secretion. Although it is present in almost all 

 scalps in which there is a normal amount of oil, it has been mostly 

 studied because of its frequent association with seborrhea, and it 

 has been considered by some investigators to be the cause of this 

 condition. The experimental data cited to support this supposition 

 are invalid because they are based on an erroneous identification of 

 the organism used.^^ Actually, Pityrosporon ovale is a tiny yeast, 

 characterized by a peculiar type of budding in which the bud is not 

 constricted at its base but is attached to the parent cell on a broad 

 surface. It will not grow on ordinary media unless some fatty sub- 

 stance such as lanolin, butter, oleic acid, or the secretions from the 

 scalp are added to the surface of the medium. (See Chapter III.) 

 A high concentration of glycerol in Sabouraud broth (up to 40 per 

 cent) inhibits the growth of bacteria and most molds, but P. ovale 

 grows on and about the epidermal scale used as inoculum and can 

 be transferred to a slant of Sabouraud agar which has been covered 

 with an ether extract of lanolin. This organism is sometimes called 

 the bottle bacillus. Another species, P. pacJujdermatis has been de- 

 scribed. It was isolated from the skin of a rhinoceros. 



Kloeckera. This term replaces the familiar Hansenia which is 

 invalid for these yeasts since it has been used earlier for another 

 organism. Cells of Kloeckera are mostly lemon-shaped or apiculate. 

 Sometimes the cells are elliptical or round. They reproduce by 



