xlii Journal of Comparative Neurology. 



6.69^ with an excitation of five minutes. If the excitation is contin- 

 ued longer than a half hour there is a strong diminution in size of the 

 cell. After excitation of one hour the diminution is .84%, after three 

 hours 11.5%, after six hours 16.53%. 



Synthetic curves based upon the measurements show that the size 

 of the cell rapidly increases during moderate activity, but under pro- 

 longed stimulation diminishes far below the normal ; that the size of the 

 nucleus follows the same law but to a less extent and less abruptly ; 

 that the size of the nucleolus increases more rapidly than the size of 

 the cell and that it diminishes under prolonged excitement much more 

 slowly. The author concludes that the size of the cell is acted upon 

 by two tendencies, one positive, activity, the other negative, fatigue. 

 Letting d represent the dimension of a cell, n the normal (average) size, 

 a the alteration due to activity, and /that due to fatigue, d will vary as 

 expressed in the following equation : 



d = 7t -]- 11 [a - f ) . 



The tardy alterations in the nucleus are regarded as consecutive 

 to those in the cytoplasm. The nuclei, contrary to Hodge and Mann, 

 do not wrinkle. 



The experiments are thus summarized : 



1. The activity of the nerve cell is accompanied by a state of 

 turgescence in the protoplasm of the cellular body. 



2. Fatigue causes a progressive diminution in the size of the cell- 

 ular body. 



3. In moderate degrees of activity, while the cytoplasm swells, 

 the nucleus suffers no modification of volume. 



4. When the activity is continuous and of long duration, the nu- 

 cleus suffers modifications analogous to these of the cellular body, but 

 less intense and slower. 



5. The quantity of chromatic substance in the cellular body va- 

 ries always as an individual character in proportion to the size of the 

 cell. Nevertheless it is probable that the first phases of cellular activ- 

 ity occasion a slight increase in its amount, the last phases accompanying 

 fatigue, a diminution and a more diffuse distribution. 



6. The activity of the cell occasions in the nucleolus an increase 

 in volume which gradually yields to the reducing action of fatigue. 



Following these experiments are some very interesting theoretical 

 observations in which attention is called to the fact that if we extend 

 the knowledge acquired of the changes in form of the body of the cell 

 to include the cellular processes also, assuming that the processes elon- 



