ISOETES. 209 



most dense tufts of slender leaves, Without having made 

 any critical observations on this point, we decidedly prefer 

 Mr. Newman's explanation, which, as would be at once re- 

 cognized by horticulturists, is quite sufficient to account for 

 the observed differences in habit among the plants. 



It is said that fish feed on the Isoetes ; and that, when 

 brought within the reach of cattle, it is greedily eaten by 

 them, and proves fattening. 



The cultivation of the Quillwort presents few difficulties ; 

 in fact, water and a little soil are the only requisites. In 

 such a miniature lake as has been recommended to be in- 

 troduced in a Wardian case fitted up for Club-mosses, this 

 plant and the Pilularia might be made to thrive ; but the 

 most interesting way in which it could be grown would be 

 in an aquatic plant-case, with transparent sides, or in any 

 substitute for such a structure, such as a glass jar of suffi- 

 cient depth. Planted in this way, its growth could be 

 watched, and many interesting points of its economy could 

 not fail to reward a careful observer. 



The aquatic plant-case, like the Wardian case, admits of 

 much variety of detail. The most useful form is probably 

 that of a rectangular glass cistern of the requisite size, held 

 together by a light metal frame, and closed in by a glass lid. 



