THE TEMPERATURE COEFFICIENT OF THE RATE 

 OF CONTRACTION OF THE DORSAL BLOOD- 

 VESSEL OF THE EARTHWORM. 



CHARLES G. ROGERS AND ELSIE M. LEWIS.' 



Certain unpublished criticisms of a previous paper of the 

 senior author 2 have led us to make a further investigation of the 

 effects of changes of temperature upon the rate of contraction 

 of the dorsal blood vessel of the earthworm. The criticism 

 offered against the previous work was that no evidence was 

 presented to show that the temperature of the forms studied, 

 worms and fish-embryos, was the same as that of the water in 

 which they were immersed. The force of the criticism is recog- 

 nized, and we are now able to present the results of an investiga- 

 tion in which the temperature of the worm studied was deter- 

 mined by means of a delicate clinical thermometer inserted in 

 the long, tubular, alimentary canal of the worm. 



We are now publishing under another title 3 an account of the 

 work in which it is shown that the temperature of the surrounding 

 water does furnish an excellent indicator of the inner body 

 temperature of the earthworm, when this animal is immersed in 

 water for experimental purposes. Inasmuch as this is true we 

 have no doubt that the previous work upon Nereis, Tubifex, and 

 the embryos of Fundulus and the toad-fish will bear the same 

 sort of inspection. 



We will not at this time take up any discussion of the literature 

 of the subject. The papers of Snyder, Robertson, Loeb and 

 Ewald and others are available for examination. The formula 

 employed for the computation of the temperature coefficients 



1 From the Department of Zoo'.ogy, Oberlin College. 



2 Rogers, Charles G., "Studies Upon the Temperature Coefficient of the Rate 

 of Heart Beat in Certain Living Animals," American Journal of Physiology, 1911, 

 Vol. XXVIL, pp. 81-93. 



3 Rogers, Charles G., and Lewis, Elsie M., "The Relation of the Body Temper- 

 ature of the Earthworm to that of its Surroundings," BIOLOGICAL BULLETIN, 1914, 

 Vol. XXVIL, pp. 261-267. 



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