18 Buchanan 



one of the many matters witli regard to which further experiments are 

 needed.^ 



III. The Same-Limb Reflex-Time in a Cord the Excitability of 



WHICH HAS BEEN RAISED BY STRYCHNINE. 



Most of tlie frogs used for these experiments were treated in the same 

 way as those used for experiments without drugs : that is to say, they were, 

 after being decerebrated, kept in the cold for one or more days before 

 making an experiment. A preparation then made in the same way as 

 has already been described for " normal " animals, but the injection into 

 the dorsal lymph sac of a very minute dose (0-005 — 002 mgr.) of strych- 

 nine some hours, or even days, before, or that of a somewhat stronger 

 dose (0-03 — 0-06 mgr.) immediately before,- never failed to produce the 

 reflex electrical response in the gastrocnemius when the mixed nerve was 

 stimulated by a single break induction shock. This response, instead of 

 being usually weaker than that to direct excitation of the efferent part of 

 the nerve, was, as a rule, of nearly equal strength with it, and sometimes 

 even stronger (rise on curve steeper). It was, however, not always its 

 strongest at the beginning. It sometimes lasted no longer than the direct 

 response, but very soon after the administration it began to lengthen, be- 

 coming from two to four times as long as the direct response. It was not 

 until the influence of the drug had become so great that it showed itself 

 in the movements of, or in the attitude assumed by, the brainless animals, 

 that the reflex electrical response began to assume the serial character so 

 often described, and capillary electrometer records of which I have 

 published elsewhere.^ In none of the photographic records reproduced in 

 the present paper does more than the first period of a response to a stimulus 

 of central origin appear, even when more were present. The undulations 

 in the contour which may be seen in most of the records reproduced in 

 figs. 4 to 12 are such as I have shown elsewhere* to be of purely muscular 

 origin, although the photographic records which really prove it have not 

 yet been published. When the effect of the strychnine begins to wear off 

 the number of periods of central (proximate and, I think, also ultimate ; 

 see p. 29, footnote) origin (recurring five to ten times a second) is reduced, 

 until finally there is again only one such period. 



Most of the experiments made for the purpose which is now concerning 

 us were made on preparations in the early stages, when the action of 

 the drug was incipient, or in the late stages, when its action was vestigial. 



' They have now been made [Nov. 1907]. 



2 I cannot state the dose in milligrammes per body weight, because I did not weigh 

 each frog. It seemed to me that little would be gained by doing so, seeing that the 

 effectiveness of the drug varies so much, and in a way that has not yet been sufficiently 

 studied, with the temperature of the frog and other conditions. 



2 Buchanan, Journ. Physiol., xxvii., 1901, Plates VIII. and IX. 



■* Burdon-Sanderson and IBuchanan, Journ. Phvsiol., xxviii., 1902; Proc. Physiol. 

 Sec, p. xxix. Garten (Abh. k. Sachsischen Ges. Wiss.,' xxvi., p. 333, 1901) has also given 

 experimental evidence of the fact. 



