212 J. BURTON ON BOTRYDIUM GRANULATUM (l.) GREV. 



substratum ; "in water they never germinate, but come to 

 rest, are surrounded by a double membrane, and lie dormant 

 for months." 



Dr. Cooke, on the authority of Kostafinski and Woronin, 

 speaks also of the development of certain spores having two 

 cilia. These conjugate sometimes in pairs, sometimes several 

 together, and produce a body called an isospore, which, after a 

 time of rest, gives rise to ordinary zoospores. But Prof. West 

 says there is good reason for doubting this process. The spores 

 met with in water have at various times been considered definite 

 organisms, and have received such names as Protococcus hotryoideSf 

 F. coccoma, and P. pcthcstris. All things considered, it is clear 

 there is much concerning this little alga wliich is at present 

 unknown, including, I am afraid, the exact form in which it 

 exists during the long periods while its habitat is covered 

 with water, preventing the development of what we look upon 

 as the definite plant Botrydium yraniUatum. 



Journ. Quekett Microscopical Club, Ser. 2, Vol. XL, No. 68, April 1911. 



