424 PROCESSES INFERRED FROM INDIRECT OBSERVATION 



Temperature- 

 interval. 



Temperature-coefficient of 

 rate of segmentation in : 



1.74 



3.3 

 3.1 

 2.8 

 2.5 

 2.6 

 2.2 

 1.7 



Temperature-coefficient 

 of rate of oxidation in : 



Arbacia. 

 2.18 



2.16 

 2.00 



2.17 



2.45 

 2.24 



2.00 

 1.96 



Not only oxidations, therefore, but some other chemical factors 

 even more susceptible to temperature change are involved in deter- 

 mining the rapidity of the cell-divisions in the early stages of develop- 

 ment. 



Other forms of growth, for example Regeneration, as A. R. Moore 

 has shown, are also affected by temperature to the extent characteristic 

 of chemical reactions. 



In all of the life-processes hitherto mentioned the general order of 

 magnitude of the temperature-coefficients has been the same. When, 

 however, we come to study the temperature-coefficients for the Dura- 

 tion of Life we meet with a startling disparity of quantitative effects, 

 for whereas, for example, it takes a rise of nearly ten degrees to double 

 the rate of the heart-beat, or the rate of respiratory movements or the 

 rate of cell-division or regeneration or tissue-oxidations, yet a tempera- 

 ture-elevation of merely one degree, as J. Loeb has shown, serves to 

 halve the duration of life of fertilized or unfertilized eggs of the sea- 

 urchin, and lowering of the temperature by ten degrees prolongs the 

 life of the organism 2 10 , that is to say over a thousandfold. The 

 temperature-coefficient of the processes underlying the thermal death 

 of the cells is therefore, no less than 1000. A. R. Moore has investi- 

 gated the influence of various temperatures upon the duration of life 

 of a hydroid, Tubularia crocea, judging viability by the retention of the 

 power of regeneration. The following are illustrative results: 



Temperature. 



25 

 26 

 27 

 28 

 29 

 30 

 31 

 32 

 33 

 34 

 35 

 36 



rature 

 10. 



3900 



485 



