sausage-shaped (Fig. 97); in the latter species the cells are frequently round or oval.

Streak cultures on yeast-water gelatine at 15° C. give, in sixteen days, colonies with distinctly hairy borders.

This species produces a more vigorous top fermentation than Sacch. Pastorianus II. It is a dangerous disease yeast which causes turbidity in beer. But a small addition of this

30

FIG. 98.-Saccharomyces ellipsoideus I., FIG. 99.-Saccharomyces ellipsoideus I., Hansen. Sediment yeast. 02. (After

Hansen.)

Hansen. Film growth at 15-13° C. 09. (After Holm in Hansen's paper.)

species to stock yeast can, in some circumstances, make opalescent beer clear, probably by removing during afterfermentation the substances which cause the opalescence.

Saccharomyces ellipsoideus I., Hansen (Figs. 79 5, 98 and 99).—This species was found by Hansen on the surface of ripe grapes in the Vosges district. The cells are of ellipsoidal shape, but may also be sausage shaped. The spores are 2 to 4 μ in size, seldom 3 to 4 μ.

At 321° C. no spores develop.

30° to 31° C. the first indications are seen after 36 hours.

The temperature limits of film formation are 33° to 34° C. and 6° to 7° C. The cells of the young film at 13° to 15° C. are distinguished from the corresponding ones of Sacch. ellipsoideus II., which are round or oval, by the large number of long, sausage-shaped cells (Fig. 99).

Streak cultures on wort gelatine at 25° C. after eleven to fourteen days give colonies with a peculiar reticulated structure (here differing from Hansen's foregoing species and from Sacch. ellipsoideus II.).

This species is one of the many which are active in wine fermentation. Numerous forms, closely related to this species, have been isolated in the experimental stations for wine culture by Aderhold, Hotter, Marx, MüllerThurgau, W. Seifert, Wortmann and others. Among these species there are some in which the cells are vigorous spore formers, e.g., the species "Johannisberg II.," which has become so well known through Aderhold and Wortmann's researches, and of which 99 to 100 per cent. of the cells develop spores on gypsum blocks. The maximum temperature for spore formation is, in this species, according to Hansen, between 33° and 343° C., and the minimum temperature between 3° and 2° C. Another wine yeast is the Walporzheim yeast. According to Aderhold this yeast is distinguished, in one respect, by the rapidity with which it forms a film in which a large quantity of spore-bearing cells appear.

Saccharomyces ellipsoideus II., Hansen (Figs. 79 6, 100 and 101), is a very dangerous disease yeast (yeast turbidity) in bottom fermentation breweries. The spores are 2 to 5 μ in size, seldom 4 to 5

μ.

At 35° C. no spores develop.

33° to 34° C. the first indications are seen after 31 hours.
29° C.

22

The temperature limits for film formation are 36° to 38°

C., and 3° to 5° C.

The cells of the young film at 13° to 15° C. are distin

guished from the corresponding ones of Sacch. ellipsoideus I. by being chiefly round or oval in shape.

Two disease yeasts isolated by Will are very closely related to this species. The cardinal points in the spore formation of these two yeasts are as follows: For one :

At 41° C. no spores develop.

39° C. the first indications are seen after 23 hours.

,, 30° to 31° C. the first indications are seen after 48 hours.

Saccharomyces Ilicis, Grönlund, was found on the fruit of Ilex Aquifolium. The cells are mostly spherical in shape. The cardinal points for spore formation are the following:

At 38° C. no spores develop.

36° to 37° C. the first indications are seen after 22 hours.

Streak cultures on wort gelatine have a mealy appearWort fermented with this species assumes a disagreeable bitter taste. It is a bottom yeast which ferments

ance.

saccharose, dextrose and maltose; in wort it produces 2-78 vol. per cent. of alcohol.

Saccharomyces Aquifolii, Grönlund, was discovered on the same fruit. It is a top yeast and, judging from the appearance of the spores, a culture yeast. The cardinal points for spore formation are the following:

At 30° to 31° C. no spores develop.

274° to 281° C. the first indications are seen after 29 hours. ,, 27° C.

28

Streak cultures on wort gelatine have a shiny appearance. This species gives to wort a sweet taste with a bitter after-taste and ferments saccharose, dextrose and maltose. In wort it forms 371 vol. per cent. of alcohol.

Saccharomyces Vordermanni, Went and Prinsen Geerligs, is, in appearance, similar to wine yeast. The cells are rounded like a pear or onion; sometimes angular or elongated cells are found. The number of spores is usually four; a film is not formed. Like all the preceding species it ferments maltose, dextrose and saccharose, the latter after inversion. It forms 9 to 10 per cent. of alcohol. The fungus is present in "Raggi," which is employed in Java in the manufacture of arrack.

Raggi" is made in the form of balls or cakes which consist of rice, pieces of sugar cane and other vegetable substances, and are saturated with organisms. Among the latter are bacteria, yeast cells and mould fungi. The presence of the first of these is not advantageous to fermentation, but rather unfavourable if they are in large quantity. The yeast cells belong partly to Sacch. Vordermanni and partly to Monilia javanica. The mould fungi are the Mucor oryza and Rhizopus oryza already described; they both turn rice starch into sugar, which is then fermented both by Sacch. Vordermanni and Monilia javanica. The first of these two fungi gives a very fine arrack, whilst the latter produces an alcohol with a bad taste. Here, therefore, a pure culture of Sacch. Vordermanni could be employed to great advantage.

Saccharomyces pyriformis, Marshall Ward, is active in the fermentation of ginger beer. The cells are similar in shape to those of the Sacch. ellipsoideus group. On wort it forms a film composed of pear or sausage-shaped cells. In conjunction with the Bacterium vermiforme, also found by Marshall Ward, it produces, from a sugar solution containing ginger, an acid frothing beverage, ginger beer, which is prepared in many cottages in England.

Saccharomyces Marxianus, Hansen, was found on grapes. The cells are small, oval or egg shaped, or elongated and sausage shaped, often in colonies. When cultures have been in wort for some time, bodies form which consist of mycelium-like colonies. When the wort cultures are two to three months old a film is just visible, consisting partly of short, sausage-shaped cells and partly of oval ones. On solid substrata Hansen observed that this species develops a mycelium which is similar, for instance, to that formed by Monilia candida. The spores are more or less kidney shaped, sometimes, however, round or oval, and usually about 3.5 μ long. After cultivation in wort they are not formed particularly easily, but are formed much more quickly and in large quantity after cultivation in a nutrient solution containing dextrose (the author).

The cardinal points for spore formation are, according to the author, as follows: maximum between 34° and 32° C., optimum between 25° and 22° C., and minimum between 8° and 4° C.

According to Hansen it gives only 1 to 13 vol. per cent. of alcohol after standing for a long time in wort. It is capable of fermenting dextrose and saccharose, the latter after inversion, but not maltose. In a 15 per cent. solution of saccharose in yeast water 3.75 vol. per cent. of alcohol were formed at 25° C. in eighteen days, and 7 vol. per cent. in thirty-eight days. In yeast water containing 10 and