Magendie on Absorption. 291 



much weaker than would have been produced in the usual 

 state of the body, by the dose submitted to absorption, and 

 were prolonged much beyond the ordinary term. 



Finally, in another experiment, where I had introduced 

 as much water (about two litres) as the animal could support 

 and remain alive, the effects were altogether imperceptible, 

 the absorption was probably prevented. After waiting near 

 half an hour for the effects which are generally developed 

 in two minutes, I reasoned as follows : if the distention of 

 the veins is the cause of the non-absorption, that cause ceas- 

 ing to operate, the absorption should take place. I there- 

 fore immediately caused the jugular vein of the animal to be 

 opened, and I saw with great satisfaction, that the effects 

 became manifest in proportion as the veins emptied them- 

 selves. 



I then thought of making the contrary experiment ; that 

 is, to diminish the quantity of blood and to see whether the 

 absorption was more rapid ; the result proved my conjec- 

 tures well founded. About half a pound of blood being ex- 

 tracted from an animal, the effects which would not have oc- 

 curred until the expiration of two minutes, manifested them- 

 selves in less than thirty seconds. 



It might nevertheless be suspected that it was less the dis- 

 tention of the blood-vessels than the alteration of the blood 

 which retarded or prevented the absorption. To overcome 

 this objection I made the following experiment ; a very co- 

 pious bleeding was practised on a dog ; the quantity of blood 

 was immediately replaced by an equal quantity of water of 

 the temperature of 40° (Centigrade) a determinate quantity 

 of the solution o^nux vomica was introduced into his pleura, 

 the effect was as prompt, and as intense as though the na- 

 ture of the blood had undergone no change.* It is then to 



* Several attempts were made which, though they could not answer the 

 purpose for which I intended them, may, nevertheless, be usefully noted 

 here, as they seem to open a new field for discoveries. 



To change the nature of the blood, I at first thought of injecting oil into 

 the veins, supposing that this innocent substance would circulate with the 

 blood without inconvenience ; the result did not answer my expectations ; 

 the animal subjected to the experiment died in a few instants after the in- 

 jection of an ounce of oil into its jugular vein. On examining the organs, 

 after the death, I observed that the oil had obstructed all the ramifications 

 of the pulmonary artery, and had thus stopped the circulation and the res- 

 piration, by preventing the passage of the blood to the left side of the heart 

 by the pulmonary veins. The oil had produced the same effect as an irievt 



