220 ATMOSFHKRICAL OXIGEN. 



t}^ continued ina6tivity of its organs, and tlie fermentation of 

 rts juices; which is occafioned by the fufpenfton of all its 

 funftions. 

 Succulent plants This fluid (o necefTary to the procefs of vegetation, is evi- 

 *hf Itmof herT ^^^^^^ abforbed from the atmofphere by fucculent plant?, bulbs, 

 but dty ones and a variety of feeds, when properly moiflened; for they will 

 feooi water. all vegetate freely in open fituations; bjut the following ex- 

 periment feeras to prove that trees, flirubs and the lefs juicy 

 herbs derive air from water, as fi flies do. 



Exp. 7. I introduced the lower extremities of di-fferent 

 plants, or more properly of the branches of different plants, 

 into phials filled with water, and after luting the necks with 

 wax, I funk the bottles in pots of water, fo as to leave th^;; 

 foliage of the plants expofed to the fun and furrounded by thei 

 atmofphere. The evaporation caufed by the adlion of the 

 light drew the water out of the bottles, and the air defcendin^ 

 at the fame time through the fubftance of the plants preventer 

 a vacuum being formed in, thefe plofe veflTels.. This facl liadP 

 nearly perfuaded me, that vegetables pofTefs a faculty analogous 

 to refpiration; but when I repeated the experiment with phiy 

 ^ als perforated in the bottom, they remained full of water. This 

 eircumdance (liews the refpiration in quefiion to be merely ac- 

 cidental and to be occationed by the necks of the bottles being 

 luted; on the other hand it is highly probable, that air enters 

 the veffels of vegetables in conjun«5lion with water. Here it 

 Is decompound, in confequence of the ftimulus given to the 

 vegetative principle by its prefence ; the azote is afterwards 

 affimulaied into the fubftance of the })lant, while the oxigen is 

 rejefled either wholly or in part. This gas, after its expUlfion 

 flows into the mephitic air, contained in the jars, the volume 

 ©f which is thereby augmented, and its quality improved ; but 

 I will not venture to fay, that the two gafes form a new che- 

 mical compound on thefe occaiions. 

 Exception to the ^^'P' ^- ^ ^^ acquainted with a Tingle exception to the ge- 

 genaral rule that neral rule that air is requifite in the procefs of vegetation. For 

 grants require ^,[^qy^ plants have withered in azote they become mouldy; that 

 is, in the language of botany, they are covered with the mu- 

 cor mucedo. The worms which inhabit the decayed livers of 

 fliecp, &c. furniHi us with a parallel inftance in the animal- 

 kingdom; and the inveftigation of thefe fingular anoraali^J 

 forms a difficult problem in the natural hiftory of organized 

 bodies.. 



The 



