270 CHARLES G. ROGERS AND ELSIE M. LEWIS. 



is the one used by Snyder in all his work, and concerning which 

 he has presented some matters of historical interest, 1 



The material used in this study was the large earthworm, 

 Lumbricus agricola. This form presents two desirable features 

 for this work; 1st, the animals are not by nature restricted to 

 any definite or narrow' limits of temperature at which their 

 normal physiological processes take place; and 2cl, it is well 

 adapted structurally for the work in that it is easily possible to 

 place a delicate temperature measuring apparatus in the ali- 

 mentary canal, and it is also easy to see the contractions of the 

 dorsal blood vessel through the more or less transparent body 

 wall. This last fact is of special importance as it makes it prac- 

 ticable to leave the animal undisturbed in its constant tempera- 

 ture bath, thus obviating any disturbance of the vascular con- 

 tractions through nervous action due to stimulation from without. 



METHODS. 



As a preliminary to the actual temperature work a number of 

 worms were subjected to immersion, for varying periods, in 

 water to ascertain what harmful effects might result. Without 

 going into detail as to this work it may be stated that the worms 

 are able to withstand immersion in tap water for a sufficient time 

 to allow all the experimentation needed for the temperature 

 studies, without showing any harmful effects. In fact certain 

 worms have been immersed for as long a period as two weeks 

 without showing any injurious effects. 



The temperatures of the worms were regulated, then, by 

 placing them in baths of water, the temperature of which was 

 controlled by placing the dishes in thermostats having practically 

 constant temperatures, in refrigerators cooled by ice, or in the 

 running water of the laboratory, which was found to have a 

 very constant temperature. 



The temperatures of the worms were determined by means of 



1 Snyder, C. D., "On an Interpolation Formula Used in Calculating Temperature 

 Coefficients for Velocity of Vital Activities, Together with a Note on the Velocity 

 of Nerve Conduction in Man," Science, N.S., Vol. XXXIV., No. 874, p. 415. 



