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Dr. E. Staehelin. On the Part played by [Dec. 11, 



muscle was equally unaffected when supplied with air which had been 

 passed over heated naphthaline. 



I also investigated the effect of certain hydrocarbons of the fatty 

 series, namely, methane, prepared by heating sodium acetate and 

 sodium hydrate, acetylene produced by the action of water on calcium 

 carbide, as well as the mixture of substances obtained by blowing air 

 through petroleum ether. In none of these cases was any effect 

 produced on the muscle. If, however, a trace of benzene was added 

 to petroleum ether, rigor mortis of the muscle was almost immediately 

 produced. In this case the volatility of the petroleum ether 

 apparently aids the evolution of the benzene. On the other hand, 

 the addition of small quantities of benzene to xylol does not impart 

 poisonous qualities to the air bubbled through the mixture, the 

 benzene being apparently held fast by the less volatile xylol. 



It seemed, therefore, most probable that the specific poisonous effect 

 of coal gas on frog's muscle was due to benzene only, and that it was 

 to the presence of this substance in coal gas that the differences 

 observed by Kunkel and Vahlen between the action of coal gas and 

 carbon monoxide were to be referred. Vahlen states that warm- 

 blooded animals and frogs die more rapidly in coal gas than would be 

 expected from its percentage of CO, and also that frogs in coal gas 

 present excitatory phenomena which are absent in pure CO. Although 

 Kunkel denies the presence of any difference between the action of 

 these two gases on warm-blooded animals, he also draws attention to 

 the peculiar effects on frogs of coal gas, which are not produced by 

 other gases free from oxygen, and describes them as " choreiform 

 twitchings and spasms in the neck and legs." To decide this question 

 the following experiments were carried out . — 



I. Three frogs were placed in air-tight bell jars, through each of which coal gas 

 was conducted at constant rate. The coal gas had to pass in each case through a 

 wash bottle, which in A was water, which, of course, left the composition of the 

 gas unchanged, in B oil, which would absorb the benzene. In front of C were two 

 wash bottles, the first one containing oil, the second one benzene. 



The passage of the gas through the three bell jars was begun at 11.20. At 11.25 

 all three frogs were restless. Frog C remained then still for a short time, and the 

 breathing became irregular, and twitching occurred in the extremities and back. 

 Movements were chiefly co-ordinated, though there were some twitchings of 

 isolated muscles. After a little time the movements became shorter and less 

 co-ordinated, the legs remained stretched out, and breathing ceased. Frog A 

 betrayed phenomena similar to C, but the spasms were less evident, and came on 

 more slowly. Frog B became qtrite quiet, the respiration becoming irregular and 

 shallower. 



At 11.40 B was sitting up in normal position, though the breathing was some- 

 what irregular, while A and C were lying on their bellies, with legs stretched out. 

 At 11.45 all three frogs were taken out. C gave no signs of life, and in ten 

 minutes was quite rigid ; B still reacted slightly to stimulation, showed shallow 

 respiratory movements, and gradually recovered, so that at 1.30 it was apparently- 

 normal. Frog A at first showed no response to stimulus, and no respiratory 



