DEBAROMYCES GLOBOSUS 221 



occurs in these mediums. There is no change in litmus milk. The 

 culture was isolated from human feces. 



Genus III. Debaromyces. Klocker 



Ascs derived by copulation. Ascospores in a single membrane, 

 the surface of which is covered with little elevations 



DEBAROMYCES GLOBOSUS. Klockei 



This species was discovered in 1909 by Klocker l in samples of 

 soil from the island of Saint Thomas. On beer wort at 25 C., the 

 cells are spherical (4.5 to 5 microns in diameter). The limits of tem- 

 perature for budding on beer wort are: maximum, 41.5 to 43; mini- 

 mum, 5 to 8 C. The ascs develop abundantly on plaster blocks at 

 32 C. The limits of temperature for the formation of ascospores are: 

 maximum, 34 to 36 C., minimum, 14 C. 



From the researches of Guilliermond, 2 it is evident that the ascs 

 result from a copulation. In about 25 per cent of the cases, this copu- 

 lation is by isogamy between 

 two cells which are more or less 

 closely situated. (Fig. 91.) In 

 all of the other cases copulation 

 occurs between an adult cell 

 and a little bud which was 

 formed by this cell, but which 

 remained attached to it (Fig. 

 28 c and 91). It is then hetero- 

 gamic. The yeast may then be 

 considered as a form in which 



heterogamy is in the process of Fi S- 91. Copulation and Formation of the 



. ,,. ., , Ascs m Debaromyces globosus. 



installing itself. Finally, par- 

 thenogenesis is very frequent, more than in the Zygosaccharomyces. 



The number of ascospores varies from one to two in each asc, one 

 being more frequent. The ascospores are globular (2 to 3.5 IJL). Their 

 surfaces present small elevations. In the center, a small globule of 

 fat is found. 



1 Klocker, A. Deux nouvelles genres de la famille des Saccharomyces. Comp. 

 Rend, des trav. du lab. de Oarlsberg, 8, 1909. 



2 Guilliermond, A. Sur un curieux exemple de parthenogenese observe dans 

 une levure. Comp. Rend. Soc. Biol. 69, 1910. Quelques remarques sur la sexua- 

 lite des levures. Annaies mycologici, 8, 1910; Sur la reproduction de Debaromyces 

 globosus et sur quelques phenome nones de retrogradation de la sexualite observes 

 chez les levures. Comp. Rend. Soc. Biol. 151, 1911. 



