NOTES ON BOTRYDIUM GRANULATUM GREV. 



HAROLD WAGER. 



General Structure and Habit. 



Botrydium granulatiim is the simplest member of the 

 group of Siphoneas, to which Vaucheria belongs. It grows 

 on damp, clayey soil or on damp mud, where it forms 

 masses of green spherical vesicles about 2 mm. or less 

 in diameter. These vesicles contain a dense layer of 

 protoplasm lining their walls, coloured deep green by 

 a large number of green chromatophores or chlorophyll 

 bodies which are present. The vesicles are rooted to the 

 ground by an extensive branching system of colourless 

 rhizoids which contain protoplasm but no chromatophores. 

 Under conditions of drought the contents of the vesicles 

 may retreat into these rhizoids, where they become rounded 

 off into separate green cells which are capable of repro- 

 ducing the plant when brought under the proper conditions. 

 The plant, therefore, can be found above ground only 

 under the most favourable conditions as regards moisture 

 and it is for this reason, probably, that so few records 

 of it, so far as I can ascertain, have been made in 

 England. 



It is, in fact, so sensitive to the environment that it 

 can exist under several conditions, and is capable of 

 different methods of reproduction according as the con- 

 ditions of the environment are varied. 



Microscopic Structure. 



According to Schmitz both the protoplasm in the green 

 vesicle above ground and in the colourless rhizoids below 

 contain very numerous nuclei, but he has given no 

 description of their structure.* 



'Sitzungsberichte der niederrheinischen Gesellschaft in Bonn, 1879-1J 



