BODY TEMPERATURE OF EARTHWORM. 



267 



galvanometer would then indicate the difference in temperature 

 between the temperature of the water and the interior tempera- 

 ture of the worm if any such difference exists. After each 

 reading the worm and free junction of the couple were placed in 

 the water of the temperature indicated for the next following 

 reading. 



The above data are representative of a large number of 

 observations made during an investigation upon the effect of 

 temperature changes upon the rate of contraction of the dorsal 

 blood vessel of the earthworm, Lumbricus agricola, and indicate 

 very clearly that the animal under investigation adapts itself 

 with remarkable quickness and closeness to the temperature of 

 its environment. In fact we think it may safely be said that the 

 worm will adapt itself to a change of at least ten degrees Centi- 

 grade within two minutes, to an accuracy of 0.05 C. This 

 fact makes it possible then to use the temperature of the water 

 surrounding the animal as an indicator of the temperature of the 

 animal, in the case of the earthworm, for experiments upon the 

 temperature coefficient of heart action, and assures us that the 

 worm need not be subjected to a bath of a given temperature 

 for any great length of time in order to get an accurate result. 

 It is very likely true that the same principle will be found to hold 

 good for other animals of a similar kind and habit, certainly 

 for marine worms, fish embryos, small Crustacea, etc. It is the 

 purpose of the authors to continue the investigation upon other 



