330 



Dr. K. Sassa. Observations on Reflex 



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the full contraction it could produce ; 

 then, after an interval of about two 

 minutes a somewhat greater rate of 

 stimulation was tried. In this way a 

 series of reflex myograms was obtained 

 at progressively increasing rates, until 

 the maximal frequency which the key 

 could give was reached. This procedure- 

 was again repeated in the reverse direc- 

 tion, i.e., progressively decreasing th& 

 stimulation-frequency to the initial rate. 



The threshold value of faradic stimuli 

 which evoked a reflex response in good 

 preparations was given by a distance 

 between the coils, of 20-35 cm., while 

 that for single induction shocks was 

 15-25 cm. 



The strongest reflex contraction was 

 in most cases obtained at a stimulation- 

 frequency of 40-60 per second. In 

 fig. 1 it is seen that the stimulation- 

 frequency of 59 per second is optimal ;. 

 the reflex reactions given at quicker or 

 slower rates than this are less powerful 

 as compared with that given at the 

 optimal rate of stimulation. The optimal 

 frequency-rate of stimulation is found to 

 be the same if it is tested in the reverse 

 direction, beginning from the highest 

 rate, and gradually decreasing to the 

 lowest. 



It must be remembered that the 

 power of reflex reaction diminishes pro- 

 gressively in a preparation which is 

 used for a prolonged experiment. This 

 is due mainly to the impairment of the 

 central nervous system, as shown by the 

 gradual subsidence of reflex excitabiKty. 

 This change does not depend on any 

 damage to the peripheral mechanism.. 



