332 (ECONOMY OF AGUATJC PLANTS. 



which a history with plates is given in the 

 sixth volume of the Linnasan Society's Trans- 

 actions, I found the drupa and all its con- 

 tents apparently perfect, except that there 

 was only a minute cavity where the embryo 

 shuld have been, in consequence of the 

 w r ant of another tree with stamens, which was 

 not to be found perhaps nearer than Japan. 

 Gardeners formerly attempted to assist Na- 

 ture by stripping off the barren flowers of 

 Melons and Cucumbers, which, having no 

 germen, they found could not come to fruit, 

 and were therefore, as they supposed, an unr 

 . sary encumbrance to the constitution of 

 trent plant. But finding they thus ob- 

 tained no fruit at all, they soon learned the 

 wiser practice of admitting air as often as pos- 

 sible to the flowering plants, for the purpose of 

 blowing the pollen from one blossom to the 

 other, and even to gather the barren kind and 

 place it over that destined to bear fruit. 



The ceconorny of various aquatic plants 

 throws great light upon the subject before us. 

 Different species of Pot amogetcn, Engl. Bot. 

 i. 168, 297, 376, &c, Ruppia maritirna, 

 f. 136, and others, float entirely under wa- 



