j^O HODGE. [Vol. VII. 



How much I was chagrined at first in not finding the curve a 

 straight line, like that for the fatigue of a muscle, I will not 

 stop to say. 



Another point of great importance, viz. that the curve of Dr. 

 Lombard, just referred to, was obtained from but a few minutes' 

 work, whereas mine represents the fatigue of ten hours, I 

 cannot discuss in full until my work upon the changes in the 

 living ganglion cell under stimulation is completed. It will be 

 sufficient for the present to remind the reader that the dots 

 showing breaks in the curve at one hour, two and one-half hours, 

 five hours, and ten hours are points taken in an entirely arbi- 

 trary manner. Had the observations been made every hour, or 

 every half-hour, the curve might have passed through the same 

 points and at the same time have been materially different. In 

 other words, there is no reason to believe that, for example, just 

 at the end of five hours fatigue began to be accelerated. This 

 point may have occurred in reality at the sixth, seventh, eighth, 

 or ninth hour, or at any time between. That is to say, the 

 points of the curve may be averages of wide fluctuations occur- 

 ring between them. Clearly, the only way to settle this point 

 is to make the intervals of observation much closer together, 

 or, as I hope to do more successfully than hitherto, to watch 

 closely the living cell during a considerable period of stimulation. 



By the continuous line in the figure is represented the proc- 

 ess of recovery in the series of rest experiments (Table IX), 

 in which five hours of severe work has caused a shrinkage of 

 the nuclei of 48.8 per cent, recovery taking place as indicated 

 by the second part of the curve. The curve of recovery, in this 

 instance, is seen to rise quite rapidly at first, then more slowly, 

 and again more rapidly to a point a little above the normal. 

 This is the exact opposite of the view given by Landois and 

 Stirling (39, p. 587) : " When a nerve recovers, at first it does 

 so slowly, then more rapidly, and afterward again more slowly." 

 However, if depth of sleep may be taken to represent rapidity 

 of recovery, then the curve given by Exner (12, p. 296) for depth 

 of sleep, with the necessary reconstruction, corresponds not so 

 badly with my own curve. 



It is not strange or anomalous that the curves of fatigue and 

 recovery should be in character alike, since both processes must 

 be of a similar nature. That is, both are processes of the liv- 



