A Note on Anaphylaxis. 



63 



protect 90 per cent, of all fully sensitized guinea-pigs. By fully 

 sensitized, we mean, that three weeks or a month should elapse 

 before the second injection of serum into guinea-pigs which have 

 survived the routine testing of antitoxin. For guinea-pigs which 

 have received horse serum alone to c.c), at least 7 or 8 

 weeks should elapse before the second injection. By allowing the 

 above elapse of time, over 90 per cent, of our controls died within 

 an hour, most of them within 20 minutes. 



We have found that the dose of the chloral hydrate per gram 

 weight of the animal was more or less variable ; no fixed amount 

 can be stated, much depending upon the individual idiosyncrasy 

 of the animal. Approximately 75 milligrams of the drug to a 

 250 gram guinea-pig and 100 milligrams to a 300 gram guinea- 

 pig produce the degree of hypnosis desired. 



We use a fresh 10 per cent, solution of chloral hydrate. We 

 carefully measure out the required amount into a small sterile 

 beaker and add an equal amount of sterile water. This diluted 

 solution is injected into the muscles of the thigh of the animal, 

 half into one leg and half into the other. After an elapse of 20 

 to 30 minutes the needle is inserted into the peritoneal cavity ; 

 muscular twitching and slight movement of the head will be 

 noticed. The injection of 5 c.c. is then given and the animal 

 kept in a warm room. No symptoms appear and the sleep is 

 undisturbed. After an elapse of i-]4 to 2^ hours the animal 

 will slowly recover from the effects of the drug. No symptoms 

 or ill effects have been observed in any of the animals. Observa- 

 tions have been followed for over two weeks after treatment. The 

 animal, after the effects of the drug have disappeared, is immune 

 to a third injection of serum, until resensitized, which will be after 

 an elapse of 2 to 2-^ months for slight sensitization and 3 to 4 

 months for full sensitization. 



If the dose of chloral hydrate has not been sufficient the in- 

 sertion of the needle into the peritoneal cavity will cause pro- 

 nounced muscular movements, the raising of the head and an 

 attempt to regain its feet. Under these conditions if the serum 

 is injected the animal will die of anaphylaxis. 



On the other hand, if the animal shows no muscular twitch- 

 ings the dose of chloral has probably been too large. 



