1. The extract of the bovine suprarenal medulla prepared by Folin Cannon and Denis' procedure was determined for epinephrine colorimetrically by Folin, Cannon and Denis and by means of the rabbit intestine segment method in parallel. The values yielded by both methods did not coincide with each other, the ratio of the colorimetrical to the biological was 1:1.1 to 1:2.1 in five experiments. 2. Of the extract of medullary tissue of bovine suprarenal capsule, made according to Suto and Inouye, the parallel estimations with the colorimetrical method of Suto and Inouye and the rabbit intestine strip test were conducted. These values also did not check with each other, and in fact the latter yielded invariably a somewhat higher value, 1:1.3 to 1:2.3 being calculated as the ratio. 3. Suto's extract cannot be simply applied to the rabbit intestine strip. The precautions taken against interfering effects are noted in the text.
By the application of liquid air for pulverizing and mixing the medullary tissue (cortex or whole gland) of the suprarenal body, we obtained the “identically uniform” material for comparing different methods of extraction and estimation for epinephrine, as those of Folin and Suto, with each other. The values of epinephrine in the suprarenal medulla of cow and ox, obtained by Folin, Cannon and Denis and by Suto and Inouye, coincide well with each other, especially in the averages, though there were noted some dissimilarities of a small degree in some individual cases. The values yielded by extracting by either Folin or Suto and estimating by the rabbit intestine segment method showed quite the same tendency. It may be therefore concluded that both methods, Folin, Cannon and Denis, and Suto and Inouye, have the same valuation for extracting and estimating epinephrine in the bovine suprarenal medulla. As to the ratio of the epinephrine content of the extract prepared by either Folin or Suto, determined colorimetrically by either Folin or Suto respectively to that estimated by the rabbit intestine strip method the present experiments yielded the same values as those given in our previous paper.2) Namely, the ratio of the colorimetrical value to the intestine value was noted as 1:2 in the averages for both the colorimetrical determinations taken altogether.
In the contraction series of the frog's gastrocnemius muscle, exposed to the air or immersed in Ringer's solution, mostly at the room temperature of 22° to 26°C., and directly stimulated 30 times per minute with maximal induction shocks, short periods of rest were introduced and the form of both the summit and base lines were observed. In general, when a contraction series was separated in groups of 30 contractions by introducing every minute a rest of 10 see., there appeared after each rest wave-like variations of the summit line in the middle part of the fatigue curve, i. e. after the finishing of the initial increase (treppe), and with beginning of the decrease of contraction height, but never in the initial and only seldom in the terminal stage. This phenomenon was most striking in the gastrocnemius of a summer frog (Rana nigromaculata). The wave-rate was 2 or 3 per minute, diminishing with the advance of fatigue. The oscillations having once appeared continued, if no further interruption by rest was made, some 2 minutes, and gradually disappeared. But as there were seen many other variation forms, evoked by introducing rest, four types of variation were distinguished. The form of the base line itself and also in relation to the summit line form was rather irregular. It was to be seen that the rise of the base line (contracture), sometimes oscillatory, occurred mostly in those fatigue curves which showed wave-like oscillations of the summit line, and not in those without these, but there were many exceptional cases. The base line rise is not the essential or coexisting condition for the production of summit line waves. The variation form, the wave-time, the time of appearing and disappearing and the time duration of waves, these all depend on several influences, among which those of the difference of individual animals, the difference of muscles, the temperature, the loading, and the stimulation rate are the most remarkable. The wave-time showed no remarkable dependence on the rate of stimulation to the extent of from 15 to 60 per minute. It decreased with the decrease of the duration of contraction, especially such as in the rise of temperature, the temperature coefficient Q10 being about 1.6. The temperature of 22°-26C. was the most favourable for the appearance of the wave-like oscillation. A high temperature above 30°C. and often also a high stimulation rate above 60 per minute were unfavourable for it. On the whole, conditions which act to hasten fatigue, such as a shorter rest time, a heavier load, a higher stimulation rate, an increase of the intensity of stimulus, a higher hydrogen-ion concentration etc. act also to hasten both onset and cessation of the waves of the summit line, and vice versa. But in many of these, the influenee was an inconsiderable one and nothing but a slight trace was to be observed. No evidence could be brought as to the facillating action of adrenaline or of hydrogen-ion (lactic acid) for the production of oscillatory variation of contraction height on introducing short periods of rest.