96 HODGE. [Vol. VII. 



gratitude, for his faithful supervision of the research during the 

 whole time, to Dr. Henry H. Donaldson. Special thanks are 

 further due to Clark University, which has provided me with 

 the best obtainable apparatus and afforded generous opportu- 

 nity for the prosecution of the work. It is with pleasure also 

 that I acknowledge my indebtedness to Professor H. Newell 

 Martin and to Professor Warren P. Lombard, for the privilege 

 of using the apparatus of their respective laboratories. 



The research has thus extended over a period of nearly four 

 years. Results have been published from time to time in the 

 American Journal of Psychology (23, 24, 25). Done from the 

 standpoint of the physiologist and morphologist, rather than 

 from that of the psychologist, I have not felt that it would be 

 appropriate to give to its publication in a psychological journal 

 the form best suited to the nature of the work. The reports 

 so far have been thus necessarily incomplete. I desire, there- 

 fore, to give a full resume of previous papers, thereby making 

 the following a unified statement of the entire research up to 

 date. This repetition is the more allowable, since, up to this 

 point, the work is a logical unit. The logical sequence from 

 the first has been determined, not by preconceived notions, but 

 step by step by the outcome of the experiments. Thus, when 

 I began by stimulating the sciatic nerve of the frog, I had little 

 enough idea that it would bring me to a study of general ner- 

 vous fatigue and restoration, and to the study of birds and honey 

 bees at morning and at night. And results still warrant further 

 prosecution of the work into the investigation of the more com- 

 plex nervous systems of the higher animals and man in conditions 

 of fatigue and disease. 



II. Theory and Purpose. 



To carry our knowledge a step farther into the working of 

 the nerve cell is the sole object of the research. We already 

 know that all the energy of the animal body comes directly 

 from chemical changes which take place in the different tissues. 

 The tissues have been specialized to perform certain chemical 

 reactions, and in the individual cells we must find epitomized 

 the function of the whole tissue. That is to say, did we but 

 know all the processes which take place in a single nerve cell, 



