442 M. H. JACOBS 



ture was found to be in the vicinity of zero. For Paramecium 

 caudatum, on the other hand, a 'surplus resistance' as high as 

 43 has been found. 



6. In general, the slower rates of temperature increase are 

 more favorable for Paramecium and more unfavorable for 

 starfish larvae than the more rapid ones. 



7. It is suggested that future data on upper thermal death 

 points, etc., shall include not only the times of exposure to the 

 temperatures in question, but exact statements as to the methods 

 by which these temperatures have been reached. 



LITERATURE CITED 



Davenport, C. B. 1897 Experimental Morphology. New York. Vol. 1. 

 Hance, R. T. 1915 The inheritance of extra contractile vacuoles in an unusual 



race of Paramecium caudatum. Science, N.S., 42. 



1917 Studies on a race of Paramecium caudatum possessing extra 



contractile vacuoles. Jour Exp. ZooL, vol. 23. 

 Kanitz, a. 1915 Temperatur und Lebensvorgahge. Berlin. 

 LoEB, J. 1908 tJber den Temperaturkoefl&zienten fiir die Lebensdauer kalt- 



bliitiger Tiere und iiber die Ursache des natiirlichen Todes. Pfliiger's 



Archiv, 124. 

 IMooRE, A. R. 1910 The temperature coefficient of the duration of life in 



Tubularia crocea. Arch. Entwick., Bd. 29. 



