ig 
in whom fatigue comes on very slowly, but commencing almost 
at the beginning of any severe muscular exertion. In others the 
exhaustion does not show itself for some time, but then it comes 
on so suddenly and emphatically that they feel quite done up, as 
they say, and can do no more. 
To show the value of a period of muscular training, before 
making the experimental tracing I will show a fourth tracing. It 
is from the finger of the same doctor as the first on the screen. It 
shews 78 contractions, as against 46, more than half of which 
were full ones. 
These curves exhibit the objective sign of muscular fatigue, 
There is a subjective sign also, viz., the sezsation of fatigue. That 
is to say, we have a physical fact which can be estimated by one 
of the instruments I have alluded to, and a psychic fact which 
cannot be estimated. With regard to the feeling of fatigue, we 
only perceive it when it has attained a certain intensity. The 
sensation of fatigue may be delayed by agreeable company, or a 
pleasant train of thought. Two friends can do a fifteen mile 
walk, providing they do not push the pace, with less signs of tiredness 
than each one going alone. The workman who persists in his task, 
after he is already fatigued, not only produces less effective work, but 
damages his organism to a greater extent. An objective sign may 
show itself before the subjective feeling comes on. In healthy 
action the muscles shorten by about one-third, but when they are 
getting tired, and sometimes even before we are conscious of the 
fact, this shortening no longer takes place, and we drag our feet, 
that is, the usual shortening does not take place to the full extent, 
and so the heels are not raised. A sense of fatigue may be 
present even before any exercise has been taken. This may be 
due to feeble circulation through the muscles, or the blood con- 
taining some poisonous products, or to its not containing its 
normal amount of oxygen. In this case a sharp walk or other 
form of active exercise improves the circulation through the 
muscle, and brings fresh supplies of oxygen, and so removes this 
pseudo fatigue. In cases of chronic fatigue there is nothing better 
than a course of massage to improve the circulation through the 
muscles, and so bring back their tone. 
Can we proceed a step farther and say what causes these 
symptoms of muscular exhaustion? Partially, at any rate, I think 
we can ; but I question whether the fiaal answer as to the cause 
can yet be given. One theory, held by a good many physiologists, 
including the Italians, is that the lack of energy in the movements 
of a weary man depends, as in the case of the frog, upon the fact 
that the muscles during work produce noxious substances which, 
little by little, interfere with contraction. Professor Mosso says 
that when the froy’s leg has become fatigued by prolonged 
exertion, we can restore its contractibility, and render it capable of 
