15 per cent. of dextrose it formed, in a month, 65 and 8 vol. per cent. of alcohol respectively.

Saccharomyces exiguus, (Reess) Hansen, was found in general in pressed yeast. This species is distinguished from the preceding one in that it does not develop mycelium-like colonies in wort nor mycelia on gelatine. The formation of spores is scanty; here also only the semblance of a film is formed after several months. Like the preceding species it is incapable of fermenting maltose. It formed 6 vol. per cent. of alcohol in a 15 per cent. solution of saccharose in yeast water. In a 15 per cent. dextrose solution 8 vol. per cent. of alcohol were formed in fourteen days at 25° C.

Formerly the opinion was held that this species was the

FIG. 102.—Saccharomyces anomalus, Hansen. Spore-bearing cells. 1909. (After Hansen.)

cause of turbidity in beer. Hansen has, however, shown that even a large addition of this fungus at the beginning or end of the primary fermentation or during storage causes no kind of disease in lager beer.

Saccharomyces anomalus, Hansen (Figs. 83 and 102), was found by Hansen in an impure brewery yeast from Bavaria. This fungus was also found later in English and Belgian beer, on green malt, on bran, in syrup of althea, in soil and on fruit, e.g., plums.

In wort it produces fermentation very soon, both at ordinary room temperature and at 25° C. At the very beginning of the fermentation a dull grey film is formed; during fermentation the liquor is turbid and a smell like fruit ether is developed. The microscopic appearance of the vegetative

ells is reminiscent of a Torula. They are small, oval and sometimes sausage shaped; many of these are found particularly in old cultures. After some time cells with spores may be found both in the film and in the sediment yeast. Two to four spores are formed in each cell; these are distinguished from the spores of all other saccharomycetes by their shape. They are, in fact, hemispherical with a projecting rim round the edge of the flat side, i.e., hat-shaped. The diameter of the flat side, not including the rim, is 2 to 3 μ. Nielsen found the following cardinal points for spore development::

At 34° C. no spores develop.

32° to 32° C. the first indications are seen after 19 to 21 hours.

The shape possessed by the spores of this species is also found in those of Endomyces decipiens, a fungus which appears as a parasite on a mushroom (Agaricus melleus), on the lamella of which it spreads itself as a whitish layer. In spite of the similarity of the spores, however, Endomyces decipiens has no genetic connection with Sacch. anomalus. Further, the spores of the latter on germinating form buds, whilst those of Endomyces form germ threads; in this latter species no budding takes place at all.

According to Nielsen's experiments, Sacch. anomalus in wort forms 09 vol. per cent. of alcohol and ester in eleven days. W. Seifert states that the ester formed here is ethyl acetate, and that in wort containing alcohol the species forms acetic acid and decomposes the alcohol into carbonic acid and water; a prolonged action of the fungus destroys the acetic ester. According to Nielsen, it causes no fermentation in maltose solutions, and secretes hardly any invertase.

Related forms have been found by Holm, Jorgensen, Lindner, Will, Zeidler and the author. Lindner found one of this kind, among others, in an Armenian beverage, "Mazun". Jörgensen states that he has found a related form in English top fermentation beer which had yeast turbidity. In bottom fermentation beer it has been observed several times, but never under such conditions that it could be looked upon as a disease yeast.

A species which also has hat-shaped spores has been named Sacch. anomalus, var. belgicus, by Lindner; it ferments neither maltose, dextrose nor saccharose, and produces no smell of fruit ester. Beijerinck describes a typical Sacch. anomalus under the name Mycoderma pulverulenta; others have also isolated new related species.

Saccharomyces membranæfaciens, Hansen, was found in a gelatinous mass which had developed on the injured roots of an elm tree. It was also found later by Koehler in the water from a polluted stream, and by Jörgensen in white wines.

The species quickly forms, on the whole surface of the wort, a strongly developed, light gray corrugated film, consisting chiefly of sausage-shaped and elongated, oval cells rich in vacuoles; wort gelatine is liquefied very quickly by it; it forms on this substratum dull gray colonies, often with a reddish tinge. They are similar to the colonies of Mycoderma cerevisiae and M. vini.

The shape of the spores is very variable; they are often rounded and sometimes inclined to a hemispherical shape. They are formed in large quantity both on gypsum blocks and in films.

This species is distinguished by its inability to form alcohol; it produces fermentation neither in saccharose, dextrose, maltose nor lactose solutions; it also secretes no invertase.

Nielsen found that

At 35° no spores developed.

33° to 33° C. the first indications are seen after 19 to 21 hours. ,, 31° to 30° C.

17 to 18

In an

W. Seifert found that Sacch. membranefaciens grows even in the presence of 12.2 vol. per cent. of alcohol. artificial nutrient liquid (Pasteur's solution) with 4.8 vol. per cent. of alcohol and an addition of malic acid it formed 0-110 per cent. of glycerine in fourteen weeks; during the same time 3.8 vol. per cent. of alcohol disappeared. It hardly attacks tartaric acid at all, nor citric acid, but malic acid. Acetic and succinic acids are completely consumed by it. The acetic acid and glycerine formed are again used up. In dextrose solutions (not in those of saccharose or maltose) it forms fixed and volatile acids. It destroys the bouquet of wine, the esters present being broken up, while new and less favourable ones are formed.

Seifert found in Crimean wine a variety which he calls Sacch. membranæfaciens var. tauricus. The latter stops growing in the presence of 12.2 vol. per cent. of alcohol. The maximum temperature for spore formation is 34° C., the minimum temperature 5° to 6° C.

Seifert also isolated another form from Californian claret, viz., Sacch. membrancefaciens var. californicus, which is capable of growing in the presence of 12.2 vol. per cent. of alcohol. The temperature maximum for spore formation is 33° C., the minimum 7° to 12° C.

Both of the latter forms are further distinguished from Sacch. membranefaciens, Hansen, by their forming much less glycerine in the above Pasteur solution and being able only to attack alcohol to a small extent.

Other related forms are described by Pichi under the names Sacch. membranæ faciens II. and III., and by Lindner under the names Sacch. hyalosporus and Sacch. farinosus.

Saccharomyces Bailii, Lindner, was isolated from Danzig Jopen beer. It ferments dextrose, inverts saccharose, and is distinguished by its developing extremely remarkable amoebiform cells in old cultures. It forms no film.

Saccharomyces mali Duclauxi, Kayser, which was found in cider, is described as follows: The cells are 6 to 12 μ long and 4 to 7 μ broad and form an easily disturbed sediment. They are moderately sensitive to acids, and die off at about 55° C. Spores appear at 15° C. in thirty hours. This yeast ferments neither saccharose nor maltose, but

ferments invert sugar and imparts a distinct bouquet to the fermented liquid.

Saccharomyces cartilaginosus, Lindner, was found in Kefir. The species ferments in wort and gives to it a somewhat smoky taste; like Sacch. Pastorianus III. it forms much frilled giant colonies and streak cultures. The plasma is peculiarly granular. On the surface of the wort after some weeks, small well-defined island colonies are formed, of somewhat compact, almost gristly consistency. Coalescence of the islands into one single layer does not take place. The sediment yeast is flocculent. In contradistinction to the following species it does not ferment milk sugar.

Saccharomyces fragilis, Jörgensen, was also found in Kefir. It ferments milk sugar. Jörgensen gives the following description: The growth consists of comparatively small oval and elongated cells. In cultures on gypsum blocks spore formation appears distinctly at 25° C. in twenty hours, at 15° C. in forty hours. The long, rounded shape of the spores is characteristic. These form both in fermenting liquids and on gelatine. In 10 per cent. lactose-yeastwater the species gave about 1 part per cent. by weight of alcohol at the room temperature in eight days; after four months it gave 4 parts per cent. by weight of alcohol. In hopped wort (about 11 per cent. Ball.) it produced about 1 part per cent. by weight of alcohol at room temperature in ten days.

By Kefir, as is well known, is understood the beverage which originated in the Caucasus and is prepared there by fermenting milk. This fermentation is brought about by the so-called Kefir grains, which are yellow, hard granules of the size of a pea. The mode of preparation in the Caucasus consists in placing the milk in goatskins to which the above corns are next added; it is then all shaken up from time to time. After a few days the drink is ready. The Kefir grains are taken out and kept for another fermentation. During fermentation, alcohol, lactic acid and carbonic acid are formed; these products are formed by the accidental co-existence of various organisms of which the number and species are

In literature Kefir fermentation and other similar fermentations (e.g., that of ginger beer) are represented and explained as the results of