CHLOROPHYCE^E 157 



shrinks into the great lumen of the cell -sap cavity 

 and leaves the plant as a translucent sphere. In 

 this condition it frequently parts company with its 

 attachment and floating to the surface is drifted 

 ashore. It is common in the West Indies, and 

 reaches Bermuda, where the plants are often 

 drifted ashore in this translucent state, and are 

 called " sea-bottles " by the inhabitants. Halicystis 

 ovalis, which resembles this plant in shape, but is 

 much smaller, occurs in the Clyde Sea area (and 

 extends from western France to the Faroes and Scan- 

 dinavia). Its systematic position is uncertain, since 

 we know nothing of its reproduction, but so far as may 

 be judged by the structure of its membrane, which 

 shows none of the striation and very little of the 

 stratification of Valonia, by its chromatophores, which 

 have no pyrenoid, while those of Valonia possess 

 one in many cases at least, and by the substitution 

 of a sucker-like disc for rhizoids, it must be placed 

 apart from Valonia. Schmitz suggests that its 

 vegetative structure recalls the freshwater Botrydium 

 most closely, and is mainly distinguished from it by 

 the absence of rhizoids. However, this is true also 

 of a comparison with Valonia, and until we know 

 its reproduction any speculation must carry little 

 weight. 



In other species of Valonia there occurs a remark- 

 able form of branching, if it may be so termed. 

 Small portions of protoplasm and chlorophyll gather 

 opposite more or less definite parts of the mem- 

 brane, generally near the apex, and separate them- 

 selves from the rest of the contents by the formation 



