108 AIR-VESSELS OF THE LEAVES* 



or shrimp, with a protuberant back, some- 

 times met with, which lives there/' — I 

 have no doubt that this shrimp feeds on the 

 other insects and worms, and that the spa 

 purposes are answered in this instance as in 

 the Sarracenice. Probably the leaves of 

 Dioncea muscipula, as well as of the Droser<z> 

 Engl, Bot. t. 867 — 869, catch insects for a 

 similar reason. 



I proceed to consider the effects of Air and 

 Light upon vegetables, 



Dr. Grew, by the assistance of the micro- 

 scope, detected a quantity of vesicles full of 

 air in the leaves of plants, as also the spiral- 

 coated vessels of their stems, which last he 

 and all other physiologists, till very lately, 

 considered as air-vessels likewise. Malpighi 

 made the same observations about the same 

 time ; and as these two acute and laborious 

 philosophers pursued their inquiries without 

 any mutual communication, their discoveries 

 strengthen and confirm each other. Their 

 books have long served as magazines of facts 

 for less original writers to work with. From 

 their remarks physiologists have theoretically 

 supposed that leaves imbibed air, which the 



