344 PHILOSOPHY OF ZOOLOGY. 



to have been first stated by FOURCROY, and afterwards es- 

 tablished by the author of the article Blood, in REE'S Cy- 

 clopedia, and by the late Dr GORDON of Edinburgh *. 



Previous to coagulation, if the atmospheric pressure be 

 removed from the blood in an air-pump, a considerable 

 quantity of air bubbles is disengaged, as was first clearly 

 established by the experiment of DARWIN-)-. VOGEL deter- 

 mined this air to be carbonic acidj; and BRANDE found that 

 two cubic inches were disengaged from every ounce of 

 blood, and that the quantity was the same in arterial and 

 venous blood ||. Even during spontaneous coagulation, 

 Mr BAUER found the blood, when confined in a glass tube, 

 to give out a considerable quantity of carbonic acid . It 

 appears, likewise, from his observations, in company with 

 Sir EVERARD HOME, that when a drop of blood is placed 

 on a watch-glass, in the field of a microscope, the following 

 changes may be perceived. " The first thing,' 1 (he says,) 

 " that happened, was the formation of a film on the surface, 

 that part beginning to coagulate sooner than the rest. In 

 about five minutes, something was seen to be disengaged 

 in different parts of the coagulum, beginning to shew itself 

 where the greatest number of globules were collected ; and, 

 from thence, passing in every direction, with considerable 

 rapidity, through the serum, but not at all interfering with 

 the globules themselves, which had all discharged their co- 

 louring matter ; wherever this extricated matter was carried, 

 a net-work immediately formed, anastomosing with itself, on 

 every side, through every part of the coagulum *[[." 



Are we to conclude from these statements, that carbonic 

 acid exists in a gaseous state in the blood ? The experi- 



Annals of Phil. vol. iv. p. 139. f Phil. Trans. 1774, p. 344. 



Annals of Phil. vol. vii. p. 56. || Phil. Trans. 1818, p. 181. 



Jbld, f Ibid. p. 182. 



