YEAST-LIKE FUNGI OF HUMAN INTESTINAL TRACT 15 



cells had elongated, and, remaining attached to each other, formed a hyphal 

 thread constricted at the ends of the cells. These 'articles' were easily broken 

 apart with the result that elongated cells were scattered among the shorter 

 budding cells. In these old cultures 'giant cells', frequently 10 times the diameter 

 of the normal cells, were present. The cell contents also changed, usually 1 

 or more large 'oil' globules appearing in each cell and frequently completely 

 filling it. In other cases no elongated or giant cells were found and the indi- 

 vidual cells were very small and showed no budding. 



The forms which these yeast-like fungi assume are various. Figure 1 rep- 

 resents, diagramatically, a series of forms ' on which the terminology in the 

 plates is based. 



The formation of a series of elongated cells does not necessarily imply 

 that the yeast concerned has given up the budding habit in favor of hyphal 

 formation and septation. In the majority of cases such series of cells are 

 formed by the apical budding of each cell in turn and the subsequent elongation 

 -of the members of this series of cells. In certain species, however, and under 

 conditions which will be explained in more detail, the cells pass over into 

 elongated mycelial threads which form true septa (Plate 3, Fig. 13) just as in 

 cell division in the other fungi. This condition, however, is rare and even here 



a 



Fig. 1. Forms of Yeast-Like Fungi: a, round; b, oval; c, elliptical; d, narrowly ellip- 

 tical; e, ovate; f, oblong; g, elongated; h, limoniform apiculate; i, amoeboid. 



the individual cells of the mycelium send out true buds, which, in turn, bud 

 in the same manner as the cells in a young culture. A large number of species 

 do not form septate hyphae under any condition so far discovered. There are, 

 therefore, 3 distinct morphologic groups in the forms studied: (1) those which 

 have only round or oval cells, (2) those which may form elongated cells but 

 do not produce septate hyphae, and (3) those which form elongated cells 

 which may pass over into septate hyphae. There is not a sharp distinction 

 between the first 2 groups but these are fundamentally different from the last. 

 In all the forms studied, even when a septate mycelium was developed, 

 there was never a tendency to form a dry, aerial mycelium, such as is pro- 

 duced by the majority of fungi when in culture. The yeasts were grown on 

 or in a very large number of mediums under a variety of conditions as to 

 moisture and temperature, but never was there an approach to aerial mycelial 

 production. This is of fundamental importance in distinguishing these forms 

 from such types as Oidium lactis, Monilia cinerea, and Blastomyces dermatitidis. 



THE BASIS OF GENERIC AND SPECIFIC SEPARATION WITHIN THE GROUP 



The forms isolated from the intestinal tract, when tested for endospore 

 formation by various standard methods, were found to be, with 2 exceptions, 

 asporogenic species. Since the majority of pathogenic fungi and a very large 

 number of the species of yeast-like organisms in* nature are of this type, the 

 following discussion will deal exclusively with tne asporogenic forms. Since 

 they have no sexual or 'perfect' stage they are naturally included in Fungi 

 imperfecti. 



