CHAPTER Vn. 



BRANCH I. PROTOPHYTA. 



TBE 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: 



J. Naked shapeless protoplasm — Sllme-moulds {Myxomycetes). 



2. Minute cells, not green — Bacteria (Sehisoms/ceies). 



3. Cells green, or greenisli — Green Slimes (CyanophycetB). 



