ACTION ON ANIMALS 125 



due, no doubt, to the fact that the intracelluiar poison is 

 liberated much more rapidly and in greater concentration 

 in the second case. As will be seen later, it is not so much 

 the absolute quantity of the poison which is injected that 

 determines the result, as the amount which is active at a 

 given time. 



The Action of the Soluble Poison. When doses of this 

 powder are given intraperitoneally in amounts varying 

 from 8 to 60 milligrams, according as to whether we have 

 been careful to remove most of the common salt or not, a 

 fatal result follows in guinea-pigs in from thirty to sixty 

 minutes. Within fifteen minutes after injection the temper- 

 ature begins to fall and sometimes within half an hour has 

 reached 94 F. or even lower. At first, after an interval of 

 from five to ten minutes immediately following the injec- 

 tion, the animal appears restless, runs about the cage, and 

 shows a great tendency to scratch itself, this undoubtedly 

 being due to itching sensations in the skin caused by irrita- 

 tion of the peripheral nerves. The animal then begins to 

 show evidence of lack of coordination, which is rapidly 

 followed by partial paralysis, which is especially marked 

 in the hind extremities. This stage lasts for from five to 

 ten minutes, during the later part of which the animal 

 usually lies quietly on one side. From this state the animal 

 passes into what one might term the convulsive stage. 

 These convulsions are usually clonic in nature and, as a 

 rule, at first involve only the neck muscles, the head being 

 momentarily drawn backward on the back. At first these 

 convulsions are but slight in degree and are separated by 

 considerable intervals of time. Soon, however, they become 

 much more frequent and of much greater severity. Gradu- 

 ually they become more and more general in their extent, 

 until all the muscles of the body become involved in violent 

 clonic convulsions. This stage when present presages a 

 fatal outcome; rarely an animal recovers after reaching 

 the convulsive stage. During a convulsion, or occasionally 

 in the interval of calm, respiration ceases. The heart, 

 however, continues to beat, at first with perfect regularity 



