RELATIVE STABILITY OF LIVING MATTER 311 



to the fact that even so stable and peculiar a compound as living 

 protoplasm may undergo prof ound alteration from causes entirely 

 external to itself. 



Moreover, this alteration is not merely temporary, but is 

 often lasting, even permanent. In the case of Ehrlich's mice, 

 already referred to, individuals which had acquired an immunity 

 represented by 200, and were then kept on normal food for 6.5 

 months, were still found resistant, certainly to the extent of $O 

 (how much more was not determined 1 ). This is in accord with 

 the experience of arsenic and opium eaters and of alcohol and 

 tobacco users : the condition is more or less permanent, and the 

 body craves the specific drug, which is no longer poisonous. 



It agrees, too, with the experience in immunity from disease, 

 which is frequently permanent through life after one attack. 

 All experiments and experience agree that immunity from one 

 poison, whether natural or acquired, is no guaranty of immunity 

 in any degree from another. 



Acclimatization to high temperatures. All experiments indi- 

 cate that death from extreme temperatures is due to coagula- 

 tion of the proteids of the protoplasm, and that ordinarily the 

 coagulation point is not far above the highest natural terrestrial 

 temperatures, so that most protoplasms are unable to resist 

 temperatures above about 45 C., having apparently become 

 nicely adjusted to natural conditions as generally encountered. 

 Yet organisms are found in the so-called boiling springs at 

 temperatures of 50, 60, 85, and even 98, which is near that 

 of boiling water. 2 Morgan mentions specifically Leptothrix, in 

 the Karlsbad springs, at 44 to 54 ; nostocs and Protococcus 

 forms in the geysers of California at 93; Oscillaria in the 

 Yellowstone Park springs at 54 to 68, in the Philippines at 

 71, in Ischia at 85, and in Iceland at 98. He remarks that 

 these temperatures may be somewhat too high, because hot 

 springs are colder at the edges than at the center ; yet the heat 

 is extreme, and far above the natural resistance of any known 

 form of protoplasm. 2 



1 C. B. Davenport, Experimental Morphology, Part I, p. 32. 



2 Morgan, Evolution and Adaptation, p. 320; C. B. Davenport, Experimental 

 Morphology, Part I, p. 252 (tables). 



