140 PROCEEDINGS OF THE ACADEMY OF [1899. 



the miuimum teDiperatures which can be resisted without loss of 

 life, but Roedel ('86) has recorded some experiments which he 

 made on fresh- water leeches. Avlastomnm gulo resisted a tempera- 

 ture of 2° C. for twelve to fifteen hours, and Clepsine comjilanata 

 a temperature of 5° C. for ninety minutes. The question whether 

 organisms can be actually frozen without consequent disorganiza- 

 tion and death has often been raised. It would seem that such 

 small, soft-bodied animals as leeches and Oligochajta must inevi- 

 tably be frozen when subjected to the conditions described above, 

 and yet they were uninjured, but the experimental proof of this 

 is inconclusive. It is significant, however, that animals with 

 thick, non-conducting external coats, as insects, centipedes and 

 snails (Roedel, '86, and Pictet, '93) resist much lower tempera- 

 tures and for a longer time than soft- bodied animals. There is 

 little doubt that the protoplasm of vertebrate tissues will withstand 

 actual freezing and recover its activity upon being thawed. • 

 Laudois and Stirling ('91) state that frogs will recover after the 

 blood has been frozen and ice has formed in the peritoneal cavity; 

 and among Pictet' s remarkable experiments it is recorded that 

 the ciliated epithelium of the frog's mouth was subjected to the 

 extremely low temperature of — 90° C. for an entire day and night 

 and yet the cilia recovered their activity when the temperature had 

 been gradually raised above 0° C. 



The internal temperature of most of the lower invertebrates rises 

 generallv less than a degree above the surrounding temperature 

 (Landois and Stirling, '91, p. 427). Metabolic activities diminish 

 with the lowering of the temperature and, in the animals (verte- 

 brates) which have been most studied, practically cease altogether 

 at the freezing point of water. 



Now this snow-worm lives and grows Avhile maintaining a bodily 

 temperature which can seldom vary much from the freezing point 

 of water. According to Mr. Brvant, it lives during the summer in 

 the melting snoAV and the water derived therefrom which collects in 

 hollows and clefts on the ice. During the night, the period of its 

 activity, when it comes to the surface of the snow, the mean temper- 

 ature of the air is about 32° Fahr. When the sun shines the worms 

 descend into the melting snow — a veritable freezing medium, which 

 must keep their small bodies continually chilled to its own tem- 

 perature. An intimate temperature relation between the worm 



