62 



Scientific Proceedings (103). 



thetization and of repeated anesthetizations after several days' 

 intervals of time were noted. The anesthetics studied were nitrous 

 oxide, ether and chloroform. In the different experiments the 

 animals were kept under anesthesia from one to five minutes and 

 observations of their behavior were begun as soon as they were 

 awake and running about. 



A difference in the effects of the different anesthetics studied 

 was very early observed. Nitrous oxide, when administered 

 carefully together with sufficient oxygen to prevent asphyxia, 

 produced the least deleterious effects. The animals recovered 

 their normal behavior or intelligence within a few minutes after 

 coming out of anesthesia. 



Numerous experiments with ether showed that the rats in this 

 case also were not much affected by the drug. On recovering 

 completely from the anesthesia, about half an hour afterwards, 

 they found their way out of the maze without going astray, but 

 showed occasionally some retardation in the duration of perfor- 

 mance. On the following day however the animals were found 

 almost invariably to have recovered completely their intelligence. 

 Even after repeated anesthetizations on different days, or after 

 prolonged single anesthetizations the same results were obtained. 



Chloroform was found to be by far the most deleterious 

 anesthetic of those studied. A single administration of the drug 

 for a minute or two was sufficient to impair the intelligence of the 

 animal for that day, and more prolonged anesthesia or repeated 

 anesthetizations produced a greater impairment of intelligence, as 

 manifested by the behavior of the animals in the maze or labyrinth 

 for several days afterwards. In some cases the impairment of 

 the mind and loss of memory were permanent or complete and 

 the animal required to be retrained before it could perform its 

 original tricks. The effect of various opiates on the behavior of 

 rats has been investigated by the authors, and will be reported at 

 an early date. 



