FURTHER STUDIES ON THE EFFECT OF VARIA- 

 TIONS IN THE TEMPERATURE ON 

 ANIMAL TISSUES. 



ARTHUR W. GREELEY. 



This paper contains an account of a series of experiments 

 which are the outcome of others of a similar nature described in 

 two earlier papers by the same author. 1 This previous work has 

 called attention to the fact, noted by other observers, that the 

 fluidity of the protoplasm of any of the Protozoa studied, varies 

 directly with the temperature up to a certain critical point (28 

 35 C), above which the protoplasm suddenly goes into heat 

 rigor, or coagulates. My own work has shown that as the tem- 

 perature is lowered below the normal, a similar coagulation sets 

 in which causes the cell to lose water. 2 This loss of water and 

 coagulation is accompanied by a gradual cessation of the vital 

 activities of the cell, and brings about certain very definite mor- 

 phological changes that result in the formation of resting cells, 

 which consist only of an undifferentiated mass of protoplasm. 

 In the case of Monas, these changes were carried further by ex- 

 posing the cells to a still greater reduction in the temperature, 

 and the resting cells were finally broken up into many small 

 spores, each of which reproduced the motile organism when re- 

 turned to the normal temperature. As the temperature is raised 

 above the normal, the protoplasm takes up water and all its vital 

 activities are accelerated, until coagulation suddenly ensues at 

 the critical point. 



1 Greeley, American Journal of Physiology, 1901, VI., p. 122. BIOLOGICAL 

 BULLETIN, 1902, III., p. 165. 



2 This fact that lowering the temperature to 1 to 5 C. and raising the temperature 

 above the critical point has the same effect upon protoplasm (i. e., coagulation and 

 loss of water), has received an interesting verification in the recent work of Fischer 

 on Lepidoptera (All. Zdt. Jilr Kntomologic, October 15, 1901). In experiments on 

 the artificial production of seasonal varieties of Vanessa anteopa by exposing the larvje 

 to different degrees of temperature, Fischer discovered that precisely the same varia- 

 tions in the adult forms are produced by lowering the temperature to 1 C. or raising 

 it to 40 C. , while modifications in the temperature within those limits gave strikingly 

 different results. 



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