SECT. XI. PHYSIOLOGY. 99 
refuted by M. Magendie. The following experi- 
ment conveys an accurate notion of absorption by 
the veins: “ M. Delille and I separated a dog’s 
thigh from his body, leaving only the crural 
artery and vein untouched, which preserved the 
communication between the thigh and the trunk. 
These two vessels were dissected with the greatest 
eare; their cellular coat was removed, for fear 
that it might contain some lymphatic vessels. 
‘Two grains of a very strong poison (I’ upas tieuté) 
were then forced into its foot ; the effects of this 
poison were altogether as rapid and as intense as 
if the thigh had not been separated from the 
‘body ; in fact, they showed themselves before the 
fourth minute, and the animal was dead before 
the tenth.” | 
ccxxx1. M. Magendie discountenances the idea, 
that venous absorption is a proof of an attracting 
power in the veins; but it is very obvious, that 
when the veins draw extraneous bodies into their 
cavities, they must do so by some power of their 
own, and irritability is quite adequate to heise 
this phenomenon. 
ccxxxu1. Three forces, then, combine in moving 
the blood in the veins, viz. the vis a tergo. com- 
municated by the heart, venal irritability, and the 
suction of the right auricle of the heart ; but the 
quantity of power which each of these forces 
contributes to the circulation, is unknown. 
