264 CHARLES G. ROGERS AND ELSIE M. LEWIS. 



the fact that certain scientific friends have raised question as 

 to the validity of the assumption upon which the temperature 

 coefficient work was based. It is with an idea of attempting to 

 answer any questions as to the propriety of assuming that the 

 temperature of the earthworm is represented by the temperature 

 of the surroundings, that the present investigation is here 

 reported. 



METHODS. 



A method of measuring differences of temperature by means 

 of the electromotive force developed when the junctions of wires 

 of different metals of a common circuit are not at the same 

 temperature was described by Nobili and Melloni 1 about 1830. 

 Since that time galvanometers have been made more sensitive, 

 and it has also been made possible to obtain pure metallic wires 

 of small diameter, and of small heat capacity. The authors 

 named w^ere the first to apply this method of temperature meas- 

 urement to living animals, and now that the methods of use have 

 been somewhat improved the same method has been employed 

 for the measurement of the amount of heat given off in a given 

 contraction of a frog muscle. 2 The method can be made accurate 

 enough to measure differences as small as 1/150 C. For the 

 purpose of the investigation here reported it did not seem neces- 

 sary to make measurements as small as those recorded by Hill, 

 so the number of junctions of the wires was not at all increased. 

 The thermo-couples used consisted of No. 32 copper and No. 32 

 constantan wires joined together as shown in Fig. i. In some 

 of the couples the wires were simply twisted together and in 

 others the junction was made secure by a small drop of solder. 

 We were not able to determine that for our purpose the soldered 

 junctions were any more efficient than those not soldered. The 

 junction used within the body of the worm was mounted within 

 a slender glass tube in such a way as to have the two wires of the 

 couple thoroughly insulated from each other except at the 

 junction point (Fig. 2). This was accomplished by placing 



1 Nobili et Melloni, "Recherches sur plusiers phenomenes calorifiques enterprises 

 au moyen du thermo-multiplcaiteur," Ann. de chimie et de physique, 1831, T. 

 XLVIIL, p. 208. 



- Hill, A. V., "The Energy Degraded in the Recovery Process of Stimulated 

 Muscles," Journal of Physiology, 1913, Vol. 46, pp. 28-80. 



