ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
681 
Growth of the Comma Bacillus on Potato.* — Dr. H. Krannhals 
records the results of numerous cultivations on potato of the comma 
bacillus made during the last epidemic at Riga. The varieties used 
were the “ Oschlapping,” a “ red ” and a <c white,” all three having been 
grown on a sandy soil. 
The potatoes were prepared in the usual way, and some pieces (105) 
were alkalized with 1/2 per cent, aqueous solution of bicarbonate of soda ; 
the rest (136) remained in their natural or “ acid ” condition. On the 
alkalized potatoes the growth of the fungus was invariably luxuriant, and 
that not only at incubation but at ordinary or room temperature. On 
the unalkalized or acid potato no growth took place in the majority 
(about two-thirds) of cases. In some instances the potato was found to 
have undergone a spontaneous alteration of reaction, being alkaline to 
litmus paper. Under these circumstances the colonies formed greyish- 
brown tufts. If, however, the potato remained acid, either no growth 
occurred at all, or if it did it was very poor, the colonies being almost 
confined to the inoculation site, and of a dirty white or pale yellow 
colour. 
The spontaneous change of reaction from acid to alkaline seems 
somewhat mysterious, but is not assignable to the growth of the fungus ; 
for, although an alkali-maker, the fungus would hardly be capable of 
producing an amount of alkali sufficient to change the reaction of the 
potato throughout the whole piece. 
Chinese Yeast and Amylomyces Ronxii.j — M. Calmette describes 
the yeast used in China and Indo-China for making wine and brandy 
from rice. It is sold in flat cakes about the size of five-franc pieces, 
and consists of a mixture of micro-organisms and various spices added 
for the purpose of imparting a flavour to the fermented liquid. The 
commercial yeast contains three kinds of micro-organisms, a fungus 
acting on and saccharizing starch, alcoholizing yeasts, and deleterious 
bacteria and moulds. By taking a piece of the “ yeast ” about the size 
of a pin’s head, rubbing it up with distilled water, dividing it into five 
equal parts, and then distributing these over five wort-gelatin plates, there 
developed eight colonies of the saccharizing fungus, 18 to 25 yeasts, two 
moulds, and thirty different kinds of bacteria. One of the last is 
called the bacillus of stringy rice, and is characterized by turning starch 
into a sticky pasty mass and preventing the formation of sugar by 
stifling with its zoogloea the saccharizing fungus, Amylomyces Rouxii. 
The exact morphological position of this schizomycete is left in doubt. It 
thrives on and in all the usual media, but beer-wort suits it best. In the 
presence of air the mycele of Amylomyces uses up the sugar formed out of 
the starch ; but when the fungus penetrates into the depth of a starchy 
medium dextrine and glucose are formed. The penetration of the 
mycele into the starch-granules is followed by the excretion of an 
enzyme (amylose) having the properties of malt diastase. Besides 
amylase the fungus also secretes sucrase. The optimum temperature 
was found to be between 35°-38°, and the diastatic power was lost when 
the temperature reached 72°. 
* Centralbl. f. Bakteriol. u. Parasitenk., xiii. (1893) pp. 33-42. 
f Ann. Inst. Pasteur, vi. (1892) p. 604. See Bot. Centralbl., liii. (1892) 
pp. 246-8. 
