8 BOTANt. 



decrease, and every time the process occurs there the result 

 is but half as many cells as before. 



Practical Studies.— (a) Carefully scrape ofE (after moistening with 

 a drop of alcohol) a little of the white, mouldy growth on lilac-leaves, 

 known as Lilaa 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) 



(b) 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 tbe 

 yeast-plants that modification of fission wliich is called budding. 

 Each yeast-plant is a minute oval cell; it first pushes out a little pro- 

 trusion which becomes larger and larger, finally equalling the first. 



In the mean lime a parlition forms be- 

 tween the two, which then separate 

 from one another. ^Fig 4, a and ft.) 



(d) Grow some yeast for a few days 

 under a bell-jar on a moist slab of plas- 

 ter, a cut potato or carrot, or even a 

 bit of moist brown paper. Upon ex- 

 Tm. 4.-Yeast-plantsreproIuc- ^mining some such yeast it will be 

 ingby diTision: n and 6 by bud- found that Some of the cells contain 

 vLlk." HfghlyyagnSld.'''"''''" several little new cells, formed by in- 

 ternal cell-division. (Fig. 4, c and d.) 

 (e) 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 maybe seen to have divided internally into four parts, each 

 of wliich 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 bright green color on account of a 

 green substance — Chlorophyll — which stains those portions 



