AND ANIMAL LIFE. 5 



tion, the blood ascends in a tube attached to the 

 jugular vein of an animal, it proves, even when 

 this act is forced, that this is its natural tenden- 

 cy, or otherwise it would not occur ; and if we 

 conceive the inspiration of a milder character, 

 the fluid will rise less, but it will not fail to 

 shew its ordinary disposition. He also observes, 

 that " the different states of the thorax cannot 

 be perceived to affect the pulse." This is very 

 true ; but it is no objection. The alternate mo- 

 tions of the thorax are obvious, and the pulse is 

 found regular when those are in their natural 

 condition, but whenever these are in atiy way 

 disturbed the former is immediately deranged, 

 shewing that the regularity of the pulse depends 

 on the regularity of the alternate motions of the 

 chest, and not that it is uninfluenced by them. 

 By taking a few deep inspirations for a minute, 

 I can raise the pulse ten beats in that period, 

 diminishing proportionably its strength ; but as 

 soon as the two acts of respiration are restored, 

 the pulse returns to its usual condition. 



IX. The early Physiologists endeavoured to de- 

 monstrate the opinion which Dr BARRY supports; 

 and this is the view that Dr CARSON has given in 

 his work on the Motion of the Blood, published 

 in 1815. " The motion of the blood, while it flows 

 in the veins, is produced by the force of the 

 heart and arteries urging it behind ; by the ab* 

 sir action of a share of the atmospheric pressure jrwn 



