ZOOLOGY AND BOTANY, MICROSCOPY, ETC, 
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6 X 3 /t; in meat extract, 9 -2 X 5*1 p, to 10*3 X 6*1 / a . It grows 
well on potato, and acquires a brilliant red tint. It does not produce 
alcohol from glucose or cane-sugar, and its development is retarded by 
3 per cent, alcohol, and altogether stopped by 7 per cent. A temperature 
of 45° for 15 minutes destroys the cells. 
S. keiskeanus. Globular cells, 5 * 1 /x-9 fx in diameter. It forms a 
faintly pink deposit in Pasteur’s solution, but the colour, probably 
owing to free oxygen, is brighter on potato. A moderate growth is ob- 
tained in starch culture or on sugar-gelatin, but the cells remain colour- 
less, whilst those on the surface gradually acquire a pink tint. The 
cells are killed by heating for 15 minutes at 50°, but not at 46°. 
Development is retarded by 5 per cent., and stopped by 7 per cent, of 
alcohol. 
Behaviour of Yeast at a High Temperature.* — According to M. 
T. Nakamura yeast is not destroyed by exposure for 1J hours at 46°, or 
for 2 hours at 48°, but is completely destroyed at 52° in 20 minutes. 
Exposure to 50° destroyed the yeast in 30 minutes, but not in 29 minutes. 
The results of other observers who found that yeast is destroyed at 40° 
are attributed to the fact that, after being heated, the fermentation pro- 
duced in Pasteur’s solution is retarded for several days. 
Experiments were made for the purpose of ascertaining the effect 
of different compounds in enabling yeast to resist the action of heat 
(50° for 30 minutes). With distilled water, cane-sugar (10 per cent ), 
sodium sulphate (1—10 per cent.), and sodium diphosphate (1-10 per 
cent.), there was no fermentation. With sodium chloride (1-10 per cent.) 
there was fermentation only after heating in 3 per cent, solution. With 
sodium nitrite (1-10 per cent.) there was fermentation only in the case 
of the 2 per cent, solution ; with meat extract there was normal fermenta- 
tion. Only the last three solutions had therefore the effect of increasing 
the resistance towards heat. 
Peculiar Movement of Intracellular Particles in Yeast-Cells.f — 
Dr. W. St. O. Symmers describes certain peculiar motile bodies which 
he first observed as far back as 1893 in a yeast. The particles and 
their movements were rendered visible when a culture was treated with 
a 4 or 5 times diluted solution of gentian -violet. Under these circum- 
stances certain yeast-cells were observed to contain a multitude of minute 
point-like bodies in a state of extremely active movement. After a while 
the particles decrease in number and increase in size from coalescence ; 
the increased size is associated with retarded movement. The process 
is continued until all the particles have fused into a single mass, almost 
filling the cell, and having only a sluggish movement. When the 
movement ceases, the pigment rapidly overspreads the cell and precludes 
farther observation of its contents. 
Since 1893 the author has observed the phenomenon in the follow- 
ing yeasts : — Saccharomyces anomalus ; ellipsoideus ; membranifaciens ; 
Pastorianus i. and ii. ; exiguus; litogenes (Sanfelice) ; a red yeast; and 
in others the exact identity of which is not established. 
* Bull. Coll. Agric. Imp. Univ. Tokyo, 1897, iii. pp. 227-30. See Journ. Chem. 
Soc., 1897, Chem. Abst., p. 577. 
t Trans. Brit. Inst. Preventive Med., 1st series, 1897, pp. 33-9 (3 figs.). 
