Page:Philosophical Review Volume 2.djvu/84

70 to be central and not peripheral, then the subjective feeling of fatigue, as well as the feeling of effort, are probably non-peripheral in their origin. Thereupon Dr. Waller gives experiments which, as he thinks, show that the diminished efficiency of our muscles when we are fatigued by voluntary exercise must be more due to exhaustion of the volitional centres than to that of the muscles themselves. In these experiments, the state of the flexor-muscles of the fore-arm was observed in various ways:

(1) By the dynamograph, a short, stiff spring, which yields but slightly to the grasp of the hand, but has its deflections magnified by a long writing lever.

(2) By the ergograph, which records the heights to which a weight is raised by successive flexions of the middle finger.

(3) By the ponograph, which registers the upward spring of the finger when, in the middle of its flexion, it is suddenly set free from the weight.

(4) By the "bag-method," an elastic bag being fixed to the arm by a leather bracelet, and connected with a Marcy's drum. This records the "hardening" or lateral enlargement of the muscle, whilst the other three methods give its longitudinal variations.

The biceps muscle was also investigated by the ponographic method.

By alternating with each other series of voluntary contractions and series got by directly faradizing the muscle and nerve, Dr. Waller found that the voluntary contractions ran down at the end of each series from fatigue, rose again at the beginning of each new series in spite of the faradization-series which had intervened. Something then recovers from the fatigue of voluntary exercise, even though energetic contractions, peripherally induced, be still going on. Since, under these circumstances, the centre is the resting organ, it must be that the previously manifested fatigue had the centre for its seat. Conversely, Dr. Waller finds the faradic tracing to show a recovery at the beginning of each fresh series, and thinks this due to peripheral rest having taken place whilst the intervening series of voluntary contractions went on. To explain such a paradox, he invokes the "end-plate." The sinking observed during each voluntary series is partly due to expansion of the end-plate, and may mask a recovery of the muscle-tissue proper from previous faradic fatigue. Müller objects (pp. 124-6) that Waller's facts are inadequate to support these conclusions as to the recovery during voluntary contraction, though he agrees that the recovery during faradization exists, and points to a central seat for at least a part of the fatigue effect observed in the voluntary series.

By using Method 4 (the "bag-method") conjointly with the dynamograph, W. found that the lateral swelling or hardening of the muscle