386 TORULACE^;. 



species discovered by him in the mucinous exudation from oak- 

 trees occasionally form strictly globular cells, each containing 

 a large drop of oil, like those of typical Torulacece. 



Whilst it is true that the diagnostic characteristics set up 

 by Hansen define the Torulacece, more sharply than was done by 

 Pasteur, recent investigations have brought to light difficulties 

 in the way of this delimitation. The Torulacece are separated 

 from the Saccharomycetes by a merely negative characteristic, 

 namely, the absence of sporulation, whereas in other respects they 

 have many points in common, both morphologically and physio- 

 logically, with the latter, as also with other asporogenic groups, 

 such as Mycoderma. Hansen himself, however, showed that some 

 of the Saccharomycetes lose their power of sporulation (see p. 260 

 et seq. vol. ii.) under certain conditions of treatment; and though 

 the occurrence of such variations in the natural state has not yet 

 been demonstrated, it is not impossible. In the absence of any 

 information as to their origin, such forms would have to be 

 grouped with the Torulacece. In the case of many Saccharo- 

 mycetes, sporulation is also known to be of very difficult and rare 

 occurrence, and one that evidently depends on certain well-defined 

 but as yet unrecognised conditions. 



The present writer's own researches have shown the existence 

 of typical Torulacece incapable of setting up fermentation with 

 the ordinary kinds of sugar, and therefore coinciding in this 

 respect with those of Pasteur. He has also become acquainted 

 with forms which, as mentioned above, produce almost exclusively 

 small, more or less globular cells under certain conditions of 

 cultivation, these cells exhibiting all the characteristics of the 

 Torulacece, and being rarely accompanied by elongated forms. 

 Under different conditions, however, the latter forms become 

 more frequent, and thus constitute an intermediate link with 

 the species forming pastorianus cells (see p. 116, vol. ii.) in 

 addition to those of oval and globular shape and mycelial 

 agglomerations of same. They also possess fermentative pro- 

 perties, thus differing from the Mi/coderma species. 



On the basis of his own investigations, the writer, in contrast 

 with Hansen, enlarges the morphological circle of the Torulacece 

 so as to include species like those characterised by Pasteur. 



Consequently, the following lines will treat not merely of 

 such budding fungi as have not yet been observed to sporulate 

 and comprising those forming exclusively more or less rounded 

 or oval cells, with or without the power of exciting fermentation 

 (first sub-group) but also of those producing mixed cells, develop- 

 ing interchangeably, but distinguished from the Mycoderma 

 species by their fermentative power (second sub-group). The 

 Monilia are excluded by the possession of a septate typical 

 mycelium (see chapter Ixii.). No fundamental reason exists for 

 excluding the so-called pink yeast (or some of them at any rate) 



