228 ELEMENTS OF BOTANY. 
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 inch in diameter, it 
may be found possible by laying a few bits of blotting-paper or card- 
board 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. 
278. Experiment 33. Can Yeast grow in Pure Water or in 
Pure Syrup ? — Put a bit of conrpressed yeast of about the size of a grain 
of wheat in about four fluid-ounces of distilled water, and another bit of 
about the same size in four fluid-ounces of 10-per-cent solution of rock 
candy in distilled water ; place both preparations in a warm place, allow 
to remain for 24 hours and examine for evidence of the growth of the 
yeast added to each. 
Fic. 198. —Two Species of Yeast, increasing by Budding. (Greatly magnified.) 
I, a species with the buds very numerous and well defined. IJ, the common 
species. 
279. Size, Form, and Structure of the Yeast Cell. —The student has 
discovered by his own observations with the microscope that the yeast 
cell is a very minute object, —much smaller than most of the vegetable 
cells which he has hitherto examined. The average diameter of a yeast 
cell is about ;,, of an inch, but they vary greatly both ways from the 
average size. (Measure an average cell in Fig. 198, H, and calculate 
about how many diameters magnifying power were used for that 
figure. ) 
The general form of most of the cells of ordinary yeast is somewhat 
egg-shaped. The structure is extremely simple, consisting of a thin cell 
wall, which is wholly destitute of markings, and a more or less granular 
semi-fluid protoplasm, sometimes containing a portion of clearer liquid, 
the vacuole, well shown in the larger cells of Fig. 198, I. 
