I. ANIMALCULA OF INFUSIONS. 0.1^ 



* ceived almoft an infinite number of modifica- 



* tions, and all are as the (hades of prifmatic co- 



' lours. 



'ferent from thofe of plants, fince In the one they are air 



* veflels, and in the other, veffels for the juices. 



* The traces of irritability only appear in certain parts 



* of fome plants, and in particular circumftances : We 



* muft explain their motions by a peculiar mechanifm, re- 



* gulated by the encreafe of the fibre, and efpecially of 



* certain parts, as well as by the changes of the fluids in 



* their veflels. 



* Vegetables do not refpire air like animals: If the leaves' 



* were lungs, moft plants would refpire none during win- 



* ter ; and if the tracheae were air veflels, tliey would not, 



* fupply the place of the leaves, fince none are in the bark, 



* By the adion of light on their leaves, plants deeompofe 



* carbonic acid and give out oxygen gas, which is very* 



* different from the carbonic acid formed and difcharged 



* by animals, for the greateft part of that formed by plants 



* in clofe veflels is a produdt from their alteration. 



* In animals, refpiration is a fource of heat: the decom- 



* .pofition of oxygen gas provides the blood with its calo- 



* ric, and difengages the fuperfluous carbon, by combni- 



* ing witli it to* form carbonic acid. But in plants, th? 



* confequence is different : the carbonic acid which de- 



* compofes by light abandons its oxygen to the caloric, 



* with which it forfns the oxygen gas that efcapes ; thus 



* depriving the plant of that fource of heat winch it might 



* derive from I'ght. Plants Jndsed foym carbonic acid by 



