PLATE I. 



Algal Types. 



1. Ci/stococciis (Protococcus). The individual cells are sur- 



rounded by terminal branches of hyphae known as 

 haustorio. 



2. Chroolepus. The branching chain of cells is enclosed by 



haustorial hyphse. 



3. Nostoc. The chains are intermingled with hyphas, which 



form no haustoria. The larger cells in the chains are 

 known as heteroci/sts. 



4. Gloeocapsa. The cells are small, enclosed by a thick strati- 



fied gelatinous covering which is penetrated by the 

 haustorial branches. 

 6. Rivularia. Algae and hyphae. In Nostoc as well as in Rivu- 

 laria the individual chains are enclosed by a gelatinous 

 substance. 



6. PobjcoccHS. Cells form colonies which are enclosed by 



haustorial hyphae. 



7. Dactijlococcus. The cells are elliptical. 



8. Pleurococcus. The cells are irregular in outline and en- 



closed by a dense hyphal structure. 



9. Sirosiphon. This is a branching many-celled alga. The 



figure represents a terminal branch. Hyphae are not 

 shown. 



