172 THALLOPHYTES 



the waters and without them animal life in the water would 

 be as impossible as animal life on the land without land plants. 

 We may also add that some articles of commerce, such as iodine, 

 are obtained from the algae, and thei time may not be far distant 

 when the enormous beds of seaweeds will prove a valuable source 

 of commercial potash for fertilizers. 



The fungi are surprisingly like the algae, but differ from 

 them in the fact that they do not possess chlorophyll. There- 

 fore, they are unable to do the work of photosynthesis and must 

 depend primarily upon organic matter, i.e., either dead or living 

 plants or animals, for their food supply. Those which live on 

 dead organic material are saprophytes and those which live 

 on living organisms are parasites. We will give brief descrip- 

 tions of the most common types. 



The yeast plants (Saccharomyces) are among, the very sim- 

 plest in structure. They are very minute, spherical, and repro- 

 duce by budding. They are found abundantly in sugary solu- 

 tions and are extremely important in alcoholic fermentations. 

 We are all familiar with their use in the making of bread. 

 Although simple in structure they have a method of reproduc- 

 tion which takes them from the lowest of the fungi. 



The common bread mould (Rhizopus nigricans) (Fig. Ill) 

 is one of the best known of the lower fungi. It occurs on stale 

 bread kept in damp places and appears as numerous delicate, 

 white threads containing protoplasm, both in the bread and erect 

 on the surface. These threads are called mycelium, but a, single 

 one is often called the hypha. On the tips of the hyphse are 

 numerous spherical sporangia or spore cases containing spores. 

 They become black with age, burst and discharge the spores 

 which are readily carried in the air. 



The sexual reproduction is by the formation of lateral 

 branches from two filaments. These branches come in contact 

 and swell, a cell-wall is formed across each and the wall at 



