Page:An introduction to physiological and systematical botany (1st edition).djvu/228

 198 or shrimp, with a protuberant back, sometimes met with, which lives there."—I have no doubt that this shrimp feeds on the other insects and worms, and that the same purposes are answered in this instance as in the Sarraceniæ. Probably the leaves of Dionæa muscipula, as well as of the Droseræ, 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 microscope, 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