208 
IOWA ACADEMY OF SCIENCE Vor. XXIX, 1922 
relaxation. The muscle is stimulated at the same rate as before 
(once per second) and is practically fatigued in about the same 
time (seven minutes). Primary contracture is certainly accom- 
panied by treppe in both methods during the first few responses 
as indicated at A. That relaxation is increased in its rate immed- 
iately following the first five or six strokes is evident by the over- 
lapping of tracing lines G' and B. The fact that this is true ex- 
presses itself in G by the successive dropping of the lower con- 
tour of successive tracing at B. Both curves give index to the 
rapid onset of secondary contracture during the progress of the 
interval labeled C, and this is soon followed by a reversal, indi- 
cated in both curves by D. On comparing curves B and G' it 
is seen that they are as characteristically different in form and 
content, as are their simultaneous counterparts B' and G. 
The effect of varying the rate of stimulation on the develop- 
ment of fatigue has of course been known for a long time. Some- 
what rapid stimulation results in the production of tetanus, while 
stimulation at a slower rate than once in four or five seconds 
postpones indefinitely the onset of typical fatigue phenomena. 
With this in mind curves A and A' were obtained where the 
stimulation was set at once in two seconds. It is seen that under 
this rate curves result which are fairly comparable to B and B', 
which were produced by a slightly faster rate (see B and B')‘. 
The treppe phenomenon is possibly more marked, primary relax- 
ation is perhaps less so. The total time interval is perhaps a little 
prolonged, consuming about nine minutes to complete, but in 
other respects no great differences are noted. 
SUMMARY 
By making simple adaptations of laboratory apparatus a method 
is described whereby both fast and slow drum types of fatigue 
records can be produced simultaneously. Such a procedure is of 
especial value in demonstrations before classes of students who 
in their general physiological course are expected to obtain re- 
cords of fatigue and make proper interpretations of such records, 
together with a reasonable amount of the theoretical implications 
of such phenomena. 
By the use of one muscle to transcribe both records comparable 
stages in the progress of fatigue processes are located on each, 
thus amplitude' and duration of responses as well as phases of 
latency, contracture and relaxation are obtainable. 
Different extreme types of fatigue records are noted, with 
