pear-shaped conidia, 4 to 11 μ, most generally 4 to 6 μ in greatest diameter. They are formed by abstriction, in part

FIG. 124.-Chalara mycoderma, Cienkowski. Connected mycelium with conidia. 43. The figure to the left shows separated mycelium branches and conidia. 10. (After Cienkowski.)

from sterigmata and partly from the surface of the limb. This species thrives on wort and lager beer. It is found in the free state on grapes and on cow dung.

Oidium lactis, Fresenius.

Oidium lactis, Fresenius (Figs. 126, 127 and 128), develops colourless, branched hypha, which form a white felt. The conidia develop by a division of the threads, and have, as a rule, a rectangular longitudinal section, but other forms are also to be observed; their length is most generally 10 to 30 μ, and breadth 3 to 5 μ. The temperature limits for the growth in wort are near 371° C. and below ° C.; for the film formation 36° to 37° C. and about 3° C.

An inter-growth similar to that observed by P. Lindner in Botrytis cinerea was found by the author and Schiönning in Oidium lactis (Fig. 128).

When, for example, a young,

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FIG. 125.-Chalara mycoderma, Cienkowski.

Mycelium members, abstricting

conidia. 118. (After Hansen.)

vigorous mycelium is seeded in a thin layer of water, a more vigorous cell here and there grows into its feebler neighbouring cell and there forms conidia chains.

This fungus is found in general on milk which has been standing. According to Hansen's investigations it generates a trace of alcohol in wort and dextrose yeast water. According to Lang and Freudenreich it can generate 1 vol. per cent. of alcohol in milk-sugar and dextrose solutions.

In breweries it is to be found on malt, lager vessels,

casks, piping, etc. It is also found occasionally on pressed yeast. Jörgensen states that he has found it in

FIG. 126.-Oidium lactis, Fresenius. 4, A branched mycelium thread m-m, distributed horizontally in the liquid medium; projecting obliquely into the air at the line c-, a branch divided by septa into a chain of cylindrical conidia, p. B, Conidia chain at the commencement of the separation of its members from each other. About 30. (After De Bary.)

large amount on top yeast when this is allowed to remain at rest after fermentation has ceased.

Oidium conidium formations have been observed by Brefeld in many mushroom fungi (Agaricinea). Some botanists are therefore of the opinion that Oidium lactis is really a stage of development of such fungi. Proof of this has not yet been advanced.

Dematium pullulans, de Bary.

The fungus (Figs. 129, 130, 131 and 132) designated by this name has a branched, colourless mycelium on the surface of which, apparently without order, it frequently produces yeast cells or conidia by budding; the latter are mostly oval. These yeast cells are often situated on the

FIG. 127.-Oidium lactis, Fresenius. The germination of a conidium in wort in a

Ranvier's chamber.

1 at 10A.M., 2 at 2 P.M., 3 at 4 P.M., 4 at 73 P. M. 3.

(After Hansen.)

threads on small humps which are sometimes discernible after the release of the yeast cells. They can then either produce more yeast cells by budding or develop germ threads, which grow into mycelia. Swollen parts are frequently found in the mycelium, which, after a certain time, become thick-walled and dark coloured, usually greenish-brown; the single cells developed by budding may also undergo transformation in this way. Gemmæ, which, among other ways, can be recognised by their contents (large oil and fat drops), are thus formed. Dematium pullulans does not induce fermentation.

Fig. 130 represents an inter-growth similar to that which has been described under Botrytis and Oidium. Such endogenous conidia have been regarded and described as endospores. The author has shown, however, in con

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FIG. 128.- Oidium lactis, Fresenius. Phenomenon of inter-growth. 59.

(After Klöcker and Schiönning.)

junction with Schiönning, that in these cases it is a matter of inter-growth only. The phenomenon is brought about when a vigorous mycelium cell in the immediate neighbourhood of a feebler cell acts as a parasite on the