104 BRITISH FERNS. 



The fructification is contained within the dilated bases of 

 the leaves, and varies with the position it occupies. The 

 spore-cases at the base of the outer leaves contain roundish 

 bodies or spores, marked on the top by three elevated ra- 

 (liating ridges. The spore-cases found at the base of the 

 inner leaves contain more numerous minute angular spores, 

 of a pale yellow colour. 



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 intro- 

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

 and the Pihdaria 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 substi- 

 tute for such a structure, such as a glass jar of sufficient 

 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 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 or cover. This would 

 require to be supported on a stand. On the bottom of the 

 interior, or projecting from the sides, proportionate-sized 

 masses of coral or other rocks should be introduced, among 

 which a little soil introduced would serve to fix and nourish 

 the plants. Thus the smaller aquatic plants might, though 

 in their proper element, be examined without difficulty, and 

 at all times. 



The proper situation for such a case would be the inside 

 of any convenient window, provided it were not too much 

 exposed to the heat of the sun ; for if placed where the sun 

 would have much influence on the temperature of the water, 

 the plants would probably suffer. Some of the very small 

 kinds of fish and the small aquatic molluscs might be intro- 

 duced with advantage, and they would impart something 

 like animation to the water. A miniature Aquarium of this 

 kind, stocked with miniature fish, and planted with thp 

 Vcdlisneria and other aquatics in the water, and with Trl- 

 ckomanes and other Ferns above, would furnish an object of 

 intense and ever-changing interest. 



