Page:The yeasts (1920).djvu/33

 saccharomyces priorianus and japonicus and S. Ludwigii. In this last variety, Hansen has proved the production of a well-developed mycelium; however, this mycelium is rarely composed of elements which are solidly united. The cells are, however, separated by well-marked walls, and each is able to thrust out buds or to develop ascospores. Certain parts of the mycelium offer very abnormal forms.

With certain species, the growth which is formed at the bottom of a flask during fermentation has a tendency to produce filamentous formations. Thus with S. marxianus has been observed the formation of little flakes of mycelium which rest on the bottom of the flask or float lightly in the liquid. Recently Lepeschkin secured with ''Sch. Pombe and mellacei'', under certain conditions, the formation of little flocks presenting all of the characteristics of a mycelium.

Mycelial formations are found well developed in a yeast described by Guilliermond in 1917 under the name of yeast from Pulque No. 2. A typical mycelium was formed of budding yeasts in most media, especially in the sediment which formed in beer wort as well as in the flocculent particles which float in the medium, on slices of carrot, and beer wort agar. The ascs seem to appear indifferently from the yeasts and from units in the mycelium.

Practically all of the yeasts divide by budding; it is the characteristic method for multiplication. The bud appears as a little prominence separated from the wall of the mother cell by a very narrow collar. Little by little it increases in size. When it has acquired a certain size, always smaller than the mother cell, it