274 THEORY OF RESPIRATION. 



process of respiration, as far as it depends on the 

 globules of the blood. It does not exclude the 

 opinion that carbonic acid may reach the lungs in 

 other ways ; that certain other constituents of the 

 blood may give rise to the formation of carbonic 

 acid in the lungs. But all this has no connection 

 with that vital process by which the heat necessary 

 for the support of life is generated in every part of 

 the body. Now it is this alone which, for the pre- 

 sent, can be considered as the object truly worthy 

 of investigation. It is not, indeed, uninteresting to 

 inquire, why dark blood becomes florid by the action 

 of nitre, common salt, &c. ; but this question has no 

 relation to the natural respiratory process. 



The frightful effects of sulphuretted hydrogen, 

 and of prussic acid, which, when inspired, put a stop 

 to all the phenomena of motion in a few seconds, 

 are explained in a natural manner by the well-known 

 action of these compounds on those of iron, when 

 alkalies are present ; and free alkali is never absent 

 in the blood. 



Let us suppose that the globules lose their pro- 

 perty of absorbing oxygen, and of afterwards giving 

 up this oxygen and carrying off the resulting car- 

 bonic acid ; such a hypothetical state of disease 

 must instantly become perceptible in the tempera- 

 ture and other vital phenomena of the body. The 

 change of matter will be arrested, while yet the vital 

 motions will not be instantly stopped. 



The conductors of force, the nerves, will convey, 



