1907.]  Post-tetanic Tremor in Several Types of Muscle. 47 
for one fibre, etc., at one moment, may not be so for that same fibre at the 
next moment. 
All the fibres are not equally fatigued after the same duration of stimula- 
tion, and, through their irresponsiveness, certain fatigued fibres rest, to recover 
their irritability later on, so that a stimulus sub-liminal for a given fibre at 
one moment may be liminal or supra-liminal for it after a short interval. 
2. In the next place, it is not probable that all the fibres composing the 
depths of a muscular mass receive either in indirect or in direct stimulation 
their stimuli at absolutely the same instant through the entire muscle—the 
bi 
so-called “non-instantaneous innervation ;” and, further, it is known that 
certain fasiculi have more component fibres than others, more fibres to be 
innervated. 
It rarely happens that all the fibres contract simultaneously, but when 
they do, we obtain a result as in fig. 4—a series of large waves of quite 
slow rhythm, 1°5 to 2 a second—reminding one strongly in some respects 
of a cardiac rhythm as seen in fig. 12, which is a record of the so-called 
“ heat-tetanus ” of the ventricle of the heart of a rabbit. 
Fig. 12.—Ventricle of heart (rabbit), immersed in continuously heated 1-per-cent.’£ NaCl. 
Lever same as in fig. 1. 5 grammes weight. Time in half-seconds. Maximal 
periodicity, 6 to 7 per second. 
In this case the gastrocnemius muscle had its circulation intact (kitten 
pithed, artificial respiration); the stimuli were from a tuning-fork in the 
primary, 7.¢., as physically uniform as possible; stimulation was direct. Here 
I conclude that the onset of fatigue was simultaneous throughout, practically, 
all the fibres of the muscle, a condition, for several reasons, very rarely met 
with (fig. 4). 
Here, if anywhere, the conditions were such as to favour the simultaneous 
onset of fatigue in the fibres, for the stimuli were as equal in intensity as 
was possible, and any conditions due to varying degrees of neural fatigue 
were eliminated by the previous fatigue of the motor end-plates; all the 
fibres were still supplied with oxygenated blood, i.e, were under the same 
conditions as regards nourishment and removal of waste-products, so that 
there was maximum uniformity of both the physical and metabolic 
conditions. 
Except for a second or two, I have seen none but irregular tracings of 
