486 
David H. Dollev 
Introduction. 
The nerve cell illustrates particularly the truth that whatever the 
type one may select priraarily for biological Investigation, whether simple 
and primitive or complex and differentiated, the necessity of weighing 
and comparing the results with those to be obtained from the other extreme 
soon becomes apparent. Up to the present work, the writer has devoted 
himself principally to the study of the functional processes as morpho- 
logically exhibited in a most highly specialized nerve cell, the Purkinje 
cell of the cerebellum. The work has included the response of this cell 
to all forms of Stimulation, both normal and, for the most part in the 
sense of being unusual, abnormal. 
Natural bodily actmties, whether occiuTing spontaneously in daily 
life or experimentally incited, as by working dogs in a treadmill, result 
not only in changes but in an identical and constant sequence of changes. 
This sequence of changes constitutes the active phase of the cycle of 
activity with its end in immediate exliaustion, and the full cycle is com- 
pleted by the subsequent recovery to the point from whicli actmty began. 
Every cell in a normal animal, whatever the degree of activity, falls into 
one Stage or another of tliis cycle. The changes grade in extent of ap- 
pearence with the severity of the work. The extremes of natural life as 
well as the extremes of experimental Stimulation differ from each other 
only in the degree and extent of the coUective changes. The purely 
natural and physiological significance of the morphological alter ations 
as representing the work of the cell rests upon this graded and constant 
occurrence and upon the inherent nature and character of the changes 
themselves. 
Further, unusual, abnormal or artificial Stimuli produce only the 
same identical changes. As types of these, the effects of mechanical 
traumatic Stimulation, inducing the condition of surgical shock, of trophic 
Stimulation in anemia, of thermal Stimulation in heat exhaustion, and of 
Chemical Stimulation from certain drugs and from bacterial toxins have 
been compared with the normal States just mentioned. 
These findings for the Purkinje cell, obtained primarily from the 
dog, have been controlled and found identical in man and rabbit and 
are in essential harmony with the results of other investigators from 
widely varying tjrpes of cells ontogenetically and phylogenetically. The 
unity of these findings led to definite conclusions regarding the nature 
and significance of the reactioh of the nerve cell in general, its mechanics, 
and its dynamic powers and limitations. To correlate the nervous activi- 
