SIMULTANEOUS FAST AND SLOW DRUM RECORDS 
OF FATIGUE 
INTRODUCTION 
FRANCIS MARSH BALDWIN 
The essential details of fatigue processes as they develop in 
a properly prepared protoplasmic system like that of a frog 
muscle, are conveniently transcribed by the writing lever either 
upon a kymograph drum revolving comparatively rapidly, or one 
going very slowly and these records furnish data for subsequent 
analysis. In each procedure some facts are obtained as to am- 
plitude, enhancing and diminution of responses under a given 
rate of stimulation and under certain physical and physiological 
conditions, but unfortunately neither method alone suffices for 
the proper analysis of the whole process. Although details of 
mechanical devices differ somewhat in the two methods the muscle 
is usually mounted in a moist chamber in such a way as to move 
at each response a counter-poised muscle lever which in turn 
transcribes its movement upon the surface of the drum. 
In using the slow drum method, an interrupter of some sort, 
which is set for a definite rhythm, usually about one stimulus 
per second, is placed in the primary circuit and a record is ob- 
tained under given conditions. Upon analysis by this method 
records usually give interesting curves whereby the comparative 
amplitude of successive contraction and relaxation phases of the 
developing fatigue process are secured. The curves also give 
evidence of increased contraction in the initial successive excur- 
sions with formation of the so-called “treppe” phenomenon and 
the accompanying production of the so-called primary contrac- 
ture phase followed almost immediately by the primary relaxa- 
tion phase merging more or less directly into the secondary con- 
tracture. Obviously, however, this method fails to record such 
comparative duration intervals as are concerned with latency, in- 
crements and decrements of irritability, as evidenced by more 
and more rapid contraction at the outset, followed by a corres- 
ponding decrement in the recovery velocity as evidenced in the 
succeeding relaxation phases. Records involving this method are 
