127 



pidly losing this superiority, and again giving out 

 nearly the whole of this air, through these same 

 blood-vessels and cells ? 



102. But if, either by the function of absorption, 

 or by the operation of chemical affinity, air did enter 

 into the blood, we may surely with reason demand 

 some proof of its presence ; yet, says Haller, " Nul- 

 ia unquam in vivo calido animali bulla aeris in san- 

 guine visa est *." This opinion is confirmed by the 

 direct experiments of Dr D. Darwin ; for having in- 

 closed a portion of the jugular vein of a sheep be- 

 tween two ligatures, it was cut out, stripped of its 

 adhering cellular membrane, and then thrown into a 

 glass of water of temperature 100, standing under 

 the receiver of an air-pump. It at once sank to the 

 bottom, and did not rise when the air was exhaust- 

 ed ; nor, when afterwards taken out, wiped dry, and 

 laid on the floor of the receiver, did it exhibit any 

 swelling under the exhaustion of the vessel. The 

 experiment was repeated with a similar result on a 

 portion of the vena cava of a swine f. 



103. Neither do the effects resulting from the ad- 

 mixture of aeriform fluids with the blood, favour the 

 notion of the entrance of air into that fluid. " Ani- 

 mal, cui aer in sanguinem inflatur," says Haller, 

 6C perit certo et velociter ; neque quidquam satis certi 

 est in sanguinis venarum pulmonalium aucto ru- 

 bore J." This assertion is confirmed likewise by 



* Prim. Lin. par. 306. 



f Philosophical Transactions, vol* Ixiv. p. 



.(: Prim. Lines, loc. cit. 



