64 



Scientific Proceedings (27). 



We wish to emphasize the fact that great care must be used 

 not to overdose the sensitized guinea-pig with chloral hydrate. 

 A sensitized, as well as a normal guinea-pig, will recover from a 

 large dose — considerably more than the amount mentioned above. 

 But, apparently, the combined effects of the drug and the serum 

 in a sensitized animal produce a deeper hypnosis than the drug 

 when given alone. 



Thus far, our experiments have been only with the intraperi- 

 toneal injection. Besredka's method of injecting directly into 

 the brain will be taken up later and also the method of injection 

 directly into the vessels according to Gay and Suthard and into 

 the heart according to Lewis. 



In a number of experiments with calcium chloride which 

 Besredka claims to have a protective action, we were unable to 

 save the sensitized animals. They died with characteristic symp- 

 toms of anaphylaxis. 



We have also failed to substantiate Besredka's claims that 

 sensitized guinea-pigs under the influence of ether narcosis are 

 protected from the second injection of ^c.c. of serum into the 

 brain. Neither does ether narcosis protect them when the in- 

 jection is made directly into the vessel or directly into the heart. 

 All the animals died with characteristic symptoms of anaphylaxis 

 in from 2 to 6 minutes. Normal control guinea-pigs under the 

 influence of ether narcosis showed no symptoms or ill effects 

 when subjected to injections of physiological saline solution by 

 the above methods. 



In conclusion, we wish to add that, other chemical substances 

 belonging to the same group as chloral may show similar action 

 in protecting guinea-pigs against anaphylaxis. 



36 (292) 



The relation of plasticity to sex and age in the dancing mouse. 

 By ROBERT M. YERKES. 



[From the Psychological Laboratory of Harvard University^ 



Plasticity or the modifiability of behavior in the dancer has 

 been studied by measurement of the rate of habit formation. The 



