8 BOTANY. 
decrease, and every time the process occurs there the result 
is but half as many cells as before. 
Practical Studies.—(a} Carefully scrape off (after moistening with 
a drop of alcohol) a little of the white, mouldy growth on lilac-leaves, 
known as Lilac Blight; mount it in water, adding a very little potas- 
sic hydrate. Some of the threads will show the formation of new 
cells (spores in this case) by fission. Other kinds of blights, as for 
example that on grass leaves or that common on the leaves of cherry- 
sprouts, furnish equally good examples. (See Fig. 79, p.156) 
(6) Strip off carefully a bit of the epidermis (skin) of a young Live- 
for-ever leaf, and mount it in water. By careful examination some 
of the cells may be observed with very thin partition-walls formed 
across them. The new walls can be distinguished from the older 
ones by their thinness. 
(c) Mount a very small drop of yeast in water and observe in the 
yeast-plants that modification of fission which is called budding. 
Each yeast-plant is a minute oval cell; it first pushe’ out a little pro- 
trusion which becomes larger and larger, finally equalling the first. 
In the mean time a partition forms be- 
tween the two, which then separate 
from one another. (Fig 4, a and 0.) 
(@) Grow some yeast for a few days 
under a bell-jar on a moist slab of plas- 
ter, wu cut potato or carrot, or even a 
; bit of moist brown paper. Upon ex- 
Fic. 4.—Yeast-plants reproduc- amining some such yeast it will be 
ing by division: a and b by bud- found that some of the cells contain 
aves are pers et a several little new cells, formed by in- 
ternal cell-division. (Fig. 4, ¢ and d.) 
(¢) Make very thin cross-sections of young flower-buds so as to 
cut through the stamens. If the specimen is of the proper age, cer- 
tain cells may be seen to have divided internally into four parts, each 
of which subsequently becomes a pollen-grain having a thick cell- 
wall of its own. 
18. Chlorophyll.—Protoplasm itself is colorless or nearly 
so, but it may make a staining substance, and stain all or a 
part of itself. Thus it is very common to find that certain 
parts of a cell are of a brigut green color on account of a 
green substance—Chlorophyll—which stains those portions 
