AND ANIMAL LIFE. 237 



CCLVI. When the par vagum was divided on 

 both sides of the neck,* the aperture of the glottis 

 was much diminished from the paralysis of its 

 muscles ; and this accounts for the difficulty of 

 breathing which almost directly succeeds the 

 operation. Although the ingress of air is, in 

 a great measure, prevented, yet the blood re- 

 turns for some time to the heart and lungs as in 

 health ; but when it arrives there it is impeded 

 in its circulation, nor does it undergo the neces- 

 sary changes ; the consequence of which is, that 

 it gradually accumulates, and ultimately renders 

 inefficient for the continuance of life, the small 

 quantity of air allowed to pass through the les- 

 sened aperture of the glottis. If this rabbit had 

 lived a little longer, we should have observed a 

 great diminution of temperature. In the second 

 of the same experiment, the thoracic disorders 

 were intermediate in degree between the first 

 and third, and yet its temperature was reduced 

 12 ; and this effect is in harmony with the first 

 general principle, viz. that animal heat is not in the 

 direct ratio of the quantity of oxygen inhaled, but 

 in the inverse ratio of the quantity of blood ex- 

 posed to this principle. 



EXPERIMENT V. 



The two rabbits employed in this experiment were be- 

 tween two and three months old, apparently healthy. 



* Vide. Appendix. 



