CHAPTER VII. 
BRANCH I. PROTOPHYTA. 
THE SEXLESS PLANTS. 
213. The protophytes are the lowest and simplest plants, 
and they are often so minute as to require the highest pow- 
ers of the microscope for their study. For the most part 
the cells are poorly developed; the protoplasm is frequently 
destitute of granular contents; the nucleus is wanting in 
many cases; and not infrequently there is either no cell- 
wall or only a poorly developed one. 
214. The cells in all cases cohere little, if at all; and even 
when they are united into loose masses each cell retains 
nearly as much independence as in the single-celled forms. 
215. No sexual organs are known. The common mode 
of reproduction is by the fission of cells, although internal 
cell-division occurs also. 
216. Most protophytes live in water and get their food 
from the solutions it contains. Some are green or greenish, 
and so are able to use carbon dioxide, while others are des- 
titute of a green color and are parasites or saprophytes. 
217. Three classes of protophytes may be distinguished, 
as follows: 
1. Naked shapeless protoplasm—Slime-moulds (Myzomycetes). 
2. Minute cells, not green—Bacteria and Yeast (Schtzomycetes). 
3. Cells green, or greenish—Green Slimes (Cyanophycee). 
