i, GENERATION. 54$ 



mud acquire two circumftances neceffary to its life 

 and growth ; one of thefe is food or fuftenance, 

 which is to be received by the abforberit mouths of 

 its veffels ; and the other is that pait of atmolphe- 

 rical air, or of water, which by the new chemiliry 

 is termed oxygene, and which affecls the blood by 

 pafiing through the coats of the veffels which con- 

 tain it. The, fluid furrounding the embryon in its 

 new habitation, which is called liquor amnii, fup- 

 plies it with nourilhment ; and as feme air cannot 

 but be introduced into the uterus along with a new 

 embryon, it would feem that this fame fluid would 

 for a fhort time, fuppofe for a tew hours, fupply 

 likewife a iufficient quantity of the oxygene for its 

 immediate exiftence. 



On this account the vegetable impregnation of 

 aquatic plants is performed in the air; and it is 

 probable that the honey-cup or ne&ary of vegetables 

 requires to be open to the air, that the anthers and 

 ftigmas of the flower may have food of a more 

 oxygenated kind than the common vegetable fap- 

 juice. 



On the in'roduclion of this primordium of en- 

 tity into the uterus, the irritation of the liquor amnii, 

 which fui rounds it, excites the abibrbent mouths 

 of the new veffels into action ; they drink up a part 

 of it, and a pleafurable fenfation accompanies this 

 new adtion ; at the fame time the chemical affinity 

 of the oxygene acts through the veffels of the ru* 

 befcent blood ; and a previous want, or difagreeable 

 fenfaiion, is relieved by this procefs. 



As the want of this oxygenation of the blood is 

 perpetual, (as appears from the inceffant neceffity 

 of breathing by lungs or gills,) the veffels become 

 extended by the efforts of pain or defne to feek 

 this neceffary object of oxygenation, and to remove 

 the difagreeable fenfation, which that want occafi- 

 ons. At the fame time new panicles of matter are 



abforbed 



