278 Messrs. N. B. Dreyer and C. S. Sherrington. 



other of the interrupted branches. It made no difference to the result 

 which one of the two branches of the circuit preceded in the sequence. 



A control of this point lay also in measui-ement of the threshold stimulus 

 for contraction as evoked by the circuit through each of its twin paths 

 respectively ; the threshold was found to be the same for both. A further 

 control was obtained by comparing the height of the reflex tetanus produced 

 («) by use of both paths, in the way above described, with the tetanus height 

 produced (/3) by use of either of the paths alone, i.e., half the frequency rate 

 of «, the secondary coil being set further from the primary coil for obs. « 

 than for obs. /3, so that the strength of the individual shocks was less for the 

 doubled frequency- rate than for the single-path frequency-rate. It was 

 found that the strength of the individual shock might be considerably less 



Two reflex responses of tibialis anticus (spinal cat) obtained in immediate suc- 

 cession, the lower to faradisation (of afferent nerve, popliteal) at 54 per sec, the 

 higher by doubling the frequency (see text) ; the higher with the coil at 

 16 cm. = 750 Berne units, the lower with coil at 14'5 cm. = about 850 Berne units. 

 Top line, 100 per sec. fork ; second line, signal for 55 per sec. interrupter. Inset: the 

 record of the vibration proper to the recording spring, lever, and attached tendon. 



during the doubled-frequency rate than during the undoubled, and the 

 resulting tetanus height yet be greater for the doubled than for the undoubled, 

 although the frequency-rate of the latter was 50 per second or over. Thus, 

 in instance, a shock-series at 110 per second, the secondary coil being at 

 100 units on the Berne scale (secondary coil 20'3 cm. from primary), gave a 

 tetanus record of 14 mm. height ; while in the same preparation the two 

 immediately preceding observations with either of the twin paths singly gave 

 a tetanus of 12 mm. height only, although for them the secondary stood at 

 150 units on the Berne scale (secondary coil 19'4 cm. from primary), the 

 frequency-rate of each of the t'win paths being, of course, 55 per second. 



The individual break-shock stimuli being similar throughout and delivered 

 throughout by the same unmoved electrode (cathode for break-shock 



