234 * Buchanan 



an excursion produced by a single induction shock was of as short a 

 duration as it was with my capillary electrometer, and that it was equally 

 short whatever the amount of the excursion, I cannot accept any evidence 

 given by his records which is not in accordance with that given by mine. 

 I cannot, that is to say, grant that for the lower-arm flexors the rhythm 

 has a constant frequency of 47 to 50 per second, as he says it has in 

 his lirst two papers, or even one varying only between 47 and 58 per 

 second [(3), p, 510]. With regard to the masseters it may be noticed that 

 he himself came to different conclusions as to their response frequency when 

 he was using different instruments. With the first [(1), p. 332] he found it 

 to be very irregular and varying between 60 and 80 per second ; with the 

 second [(2), p. 412] he found it to be 60 to 64 per second ; with the third 

 [(3), p. 509] 88 to 100 per second. Judging from the unpublished masseter 

 records which he has been kind enough to let me see, taken, I believe, with 

 the third instrument, I should myself have said that the response was 

 characterised by greater regularity than was obtained with any other muscle, 

 and that, when most regular, frequencies of 96, 100, 115 or 120 per second 

 prevailed, although elsewhere it was sometimes 70 to 80 per second. My 

 own records also show a more regular response with this muscle than is, as a 

 rule, obtained with the flexores digitorum, although the frequency in the one 

 person whose masseter response I have i-ecorded was as high as from 170 to 

 200 per second. Some of Piper's other records, referred to, but not pub- 

 lished, in his third paper, taken with several different muscles for a few 

 seconds at a time, would also seem to me to show, as my own records do, 

 that now one response frequency obtains, now another. With the gastro- 

 cnemius, for instance, I should have said that the records he sent me showed 

 that frequencies of 73, 87, and 100 per second prevailed rather than the 44 

 which he estimates it at ; with the extensor pollicis brevis 63 per second 

 rather than 47 to 50 ; with the quadriceps femoris I would agree with 

 him that one of the prevailing frequencies is about 44 per second, but I 

 find others in the same, or in other records, of 52, 66, and 76 per second. I 

 am, of course, counting something different from what he is, but the fact 

 that two people may come to such different estimates with regard to the 

 frequency from the same records shows the need for something more 

 striking than he has yet given us, in the way of evidence that the muscles 

 supplied from any one special centre in the cord or in the medulla oblongata 

 all exhibit the same response frequency [(3), p. 516]. 



To my second conclusion (p. 231), that the rhythm observed originates 

 in the muscle rather than in the central nervous system. Piper raises 

 two objections [(1), p. 328], namely: — 



(i.) That if the rhythm were not due to the central nervous system, we 

 should expect to see in the records indications of another, and slower, 

 rhythm as well, and that we do not. I do not see the necessity for expect- 

 ing it. It by no means always appears, as I have shown (both in 1901 and 

 in the present paper) in reflex responses of frog's muscle, even when in 



