American journal of physiology . rapidity with which the nerve dried whenexposed to high temperatures. As to the temperatures of thestretch b a word should be said. It will be noticed in the reportsof the experiments that the temperatures producing the same effectsdiffer somewhat. This is due to the fact that the method varied alittle; for, as already mentioned, the tunnel was at first divided intothree parts, which, to eliminate the danger of drying, were subse-quently united. In this united condition the two cooler streamstended to counteract the warm stream, thus necessitating an eleva-tion
American journal of physiology . rapidity with which the nerve dried whenexposed to high temperatures. As to the temperatures of thestretch b a word should be said. It will be noticed in the reportsof the experiments that the temperatures producing the same effectsdiffer somewhat. This is due to the fact that the method varied alittle; for, as already mentioned, the tunnel was at first divided intothree parts, which, to eliminate the danger of drying, were subse-quently united. In this united condition the two cooler streamstended to counteract the warm stream, thus necessitating an eleva-tion of the temperature of the latter. Figure 4. — Curve for strong stimulation. Froman experiment of Nov. 17. Fresh nerve; de-marcation current at beginning of experiment= 88 mm.; demarcation current at end ofexperiment = 66 mm. Ordinates expressstrengtli of action current; two ruled divisionsare equal to 1 mm. of scale deflection ; tem-perature of stretch h given above; intervalsbetween observations, in minutes, along Infiiience of Temperature upon Nervous Conductivity. 315 Upon consulting the accompanying typical curve for a strongstimulus, i. e. a stimulus producing almost or quite a maximalgalvanometric response, it will be seen that there is no increase inthe action current as the temperature of the stretch b is raised(Fig. 4) ; no change is observed until the temperature is sufficientlyhigh to cause a decrease. With a maximal stimulus and whenthe temperature of the stretches a and c was not far from roomtemperature this has been my uniform experience. If we call thetemperature which the whole nervehas before the changes in the tempera-ture of the stretch b begin, the base-line temperature, we may state thatfrom a base-line temperature between15° and 25° there is no increase in theaction current when the nerve impulsehas to pass through a heated area,provided a strong stimulus has beenused. If the base-line temperature be aslow as 10°, there may be an increas
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