UNICELLULAR FORMS 



11 



Phylum Thallophyta 

 (Simple. Often single 

 cells. Lack true tis- 

 sues.) 



Schizophyta f Blue-green alga^ 



(Reproduce by fission) [bacteria 



Algas — Contain chlorophyll. Seaweeds, 

 Pond Scums. 



Fungi 



(No chlorophyll) 



YEASTS 



Molds 

 Smuts 

 Mushrooms 

 Puffballs 



Phylum Bryophyta. Mosses and their allies. 



Phylum Pteridophyta. Ferns. 



Phylum Spermatophyta. Seed-bearing plants. 



The yeast plant, one of the Fungi, in its saprophytic nutrition strik- 

 ingly illustrates a chemical process of metabolism that in some 

 form or other is carried on in the cells of all plants and animals 

 and is one of the most important of 

 the metabolic phenomena. This proc- 

 ess is enzyme action. 



The yeast plant consists of single 

 cells, or chains or loose groups of cells. 

 Different species of yeast cells may be 

 cylindrical, ellipsoidal, or spherical in 

 shape (Fig. 24) . Yeasts reproduce by a 

 modified form of fission called bud- 

 ding, in which the parent cell does not divide into two equal cells, 

 but gives off a small daughter cell or cells, which may remain 

 attached to the parent for a time. At moderately high room tempera- 

 ture the yeast plant multiplies with considerable rapidity. The com- 

 mon yeasts live quite well in sugar solutions and obtain their energy 

 by breaking down the sugar into carbon dioxide and alcohol. The 

 general name for this process is fermentation, but organisms per- 

 form many such processes, so the term fermentation does not 



Fig. 24. — Yeast plants. 



