CHARACTER OF THE CORTICAL CONTRACTIONS. 707 



day. 1 It is about this time that the fibres of the pyramidal tract begin to be 

 myelinated in the dog. 2 



ON THE CHARACTER OF THE MUSCULAR CONTRACTIONS WHICH ARE 

 EVOKED FROM THE CEREBRAL CORTEX. 



If a tracing is taken by any form of myograph (Fig. 319) of the 



FIG. 319. Method of recording the voluntary contraction-curve of opponens pollicis. (A] 

 Receiving tambour, the button of which rests against the muscle ; (B] recording 

 tambour ; (C) time-signal. 



Fro. 320. Tracing of a voluntary contraction of the thumb muscles, taken with a trans- 

 mission myograph on a slowly moving surface. The intervals between the vertical 

 lines represent seconds. To be read from left to right. 



voluntary contractions of a muscle, the curve which is obtained exhibits 

 waves, irregular in amplitude but fairly regular in rate, and exhibiting 



1 Soltmann, Jahrb. f. Kinderh., Leipzig, 1876, Bd. ix. S. 106 ; Steiner, Sitzungsb. d. k. 

 Akad. d. JFissensch., Wien, 1895, S. 303. 



2 Bechterew, Abstract in Neurol. CentralbL, Leipzig, 1888, S. 14; and 1889, Bd. viii. 

 S. 513. 



