246 Journal of Comparative Neurology. 



Plasticite Morphologique des Neurones Cerebraux, 1896), ob- 

 tained precisely similar findings in animals poisoned with mor- 

 phine, chloral hydrate, chloroform and also in those whose cer- 

 ebral cortex had been stimulated electrically (for only five min- 

 utes). He also investigated, in no very adequate manner, nor- 

 mal conditions of rest and fatigue, but with wholly negative 

 result. 



The following experiment was devised to obtain prepara- 

 tions of nerve cells quickly enough, if possible, to catch them 

 in their sleeping and waking states. It consisted simply in cut- 

 ting through the entire head of the animal at a single blow with 

 a very sharp thin knife, the parts of the head falling instantly 

 into large culture dishes of Cox's solution, warmed to 39° C. 

 In the two experiments to be described puppies, about seven 

 weeks old, were used, sisters from the same litter. It was hoped 

 by using the surfaces coming first in contact with the killing 

 fluid, to obtain the cells before they could extend or retract, in 

 case their processes actually changed position. 



In the first experiment one puppy was killed at 4 o'clock 

 P. M., awake, though rather sleepy, after having played about 

 actively the greater part of the day. The sister puppy was 

 kept awake from this time until 7 P. M. of the same day, 

 when she was allowed to go to sleep. Thinking that sleep 

 might reach its maximum depth in about i )^ hours, it was in- 

 tended to cut the brain at 8:30. However, after sleeping sound- 

 ly until 8:05 she suddenly opened her eyes,, yawned, stretched 

 and got up, evidently pretty well awake. By very gently lay- 

 ing her in position again, however, she was asleep by about 

 8:10 and the cut was made, after being asleep again for only 5 

 minutes, at 8:15. Results of the experiment may be seen in 

 the following table, as related to the pyramidal cells of the cer- 

 ebral cortex. 



Puppy awake, Puppy asleep, 

 4 P. M. 8:15 P. M. 



Cells with dendrites not varicose, 211 107 



Cells with dendrites slightly varicose, 36 3 



Cells with considerable varicosity of dendrites, 12 6 



Cells with much varicosity, 49 i 



Whole number studied, 308 117 



Cells showing varicosity, S'-i?^ 8-5% 



Cells with much varicosity, "^S-^fo 0.8% 



