TYPES OF CRYPTOGAMS; THALLOPHYTES 231 
stand in a warm place for some hours after the exposure to hot 
water. What has happened to the yeast-plants? 
(f) The behavior of a lighted match lowered into the air space 
above the liquid in the large bottle, after the latter has been standing 
undisturbed in a warm place for an hour or more. 
(g) The smell of the liquid and its taste. 
297. Microscopical Examination of the Sediment.1— Using a very 
slender glass tube as a pipette, take up a drop or two of the liquid 
and the upper layer of the sediment and place on a glass slide, cover 
with a very thin cover-glass, and 
examine with the highest power 
that the microscope affords. 
Note: 
(a) The general shape of the 
cells. 
(b) Their granular contents. 
(c) The clear spot or vacuole 
seen in many of the cells. 
Sieeheh, poms. .ch “ue ae Fic. 166. Yeast (Saccharomyces 
and compare the sketches with ellipsoideus) budding actively. 
Fig. 166. : 
RinieiGeniionhien ee oe 
ding cells; C,alarge group. }, buds. 
under one edge of the cover-glass, =~ 
at the same time touching a bit of blotting paper to the opposite edge, 
and notice the color of the stained cells. Do they contain starch? 
Place some vigorously growing yeast on a slide under a cover- 
glass and run in a little eosin solution or magenta solution. Note 
the proportion of cells which stain at first and the time required 
for others to stain. Repeat with yeast which has been placed in 
a slender test-tube and held for two or three minutes in a cup of 
boiling water. 
With a very small cover-glass, not more than three-eighths of an 
inch in diameter, it may be found possible, by laying a few bits of 
blotting paper or cardboard on the cover-glass and pressing it against 
the slide, to burst some of the stained cells and thus show their thin, 
colorless cell-walls and their semi-fluid contents, protoplasm, nearly 
colorless in its natural condition but now stained by the iodine. 
1 See Huxley and Martin’s Biology, under Torula. 
