380 USE OF ARTIFICIAL RESPIRATION AND TRANSFUSION. 



death. It is a very powerful poison, certainly ; but there is a 

 limit to its virulence ; and, if there be too little of it in the 

 blood, it will have no action. On this account it is not usually 

 poisonous when swallowed, for it is excreted by the kidneys as 

 quickly as it is absorbed from the stomach, and so there is 

 never enough in the blood at any one time to produce any effect 

 whatever on the body. The result is very different, however, 

 when the kidneys are prevented from acting, by ligatures 

 applied to the ureters. Then the poison, which is gradually 

 absorbed from the stomach, goes on accumulating in the blood, 

 and by-and-by, when it has reached the necessary amount, it 

 produces exactly the same effects as if it had been injected 

 directly into the veins. When the poison is applied to a wound, 

 it is usually absorbed more quickly than the kidneys can 

 excrete it, and so poisoning occurs. But, if a ligature be applied 

 above the wound so as nearly to stop the circulation, the 

 absorption of the poison may be hindered so much that it is not 

 taken up from the wound any faster than the kidneys can 

 excrete it. Thus the whole of it may be got rid of, without its 

 ever being able to produce any toxic effects whatever. If the 

 circulation be allowed to go on at all in the wounded part, it is 

 rather difficult to regulate it exactly enough to ensure that too 

 much poison shall not be absorbed at once. It is, therefore, 

 better to apply the ligature so tightly as to stop the circulation 

 altogether, and only remove it occasionally for a few seconds at 

 a time. In this way it is easy to control the absorption of the 

 poison by removing the ligature wdth more or less frequency, 

 and leaving it of[' for a longer or shorter period, as seems 

 advisable. But it is not by regulating the absorption of woorara 

 only that we are able to prevent its toxic action. Even when a 

 large quantity is circulating in the blood, and the animal seems 

 j)erfectly dead, recovery is still possible. 



The woorara, curare, or ticunas poison — for it has all these 

 names and several more — has little or no action on either the 

 l)rain or the muscles ; but, as Bernard has shown, it paralyses 

 the motor nerves ; and so the rhythmical nervous impulses 

 which the medulla usually sends to the muscles of respiration 

 cannot be transmitted, and breathing ceases. Many years before 



