CAUSES OF NECROSIS 311 



In just what way lack of nourishment causes death has not 

 been determined, but, as has been before suggested, it seems 

 probable that it is because catabolic processes are no longer 

 balanced by anabolic processes, and with these latter oxidizing 

 enzymes seem to be inseparably associated, so far as our present 

 knowledge shows us. Were it not that the proteolytic enzymes 

 continue in action after nutrition is shut off, the cells might 

 remain in a completely unaltered condition for an indefinite 

 period, and capable of resuming their functions when nourish- 

 ment is again supplied, which is decidedly contrary to the facts. 

 (The general features of anemic necrosis have been already dis- 

 cussed in the preceding paragraphs, and also under the subject 

 of infarction.) 



Thermic Alterations. These have been studied partic- 

 ularly in connection with the cells of the lower organisms. 1 

 While some unicellular organisms can survive a temperature of 

 69, most of them are killed at from 40-45. For the great 

 majority of metazoa the maximum temperature lies below 45, 

 and in the case of marine species below 40. 2 The heating is 

 accompanied by the appearance of granules in the cytoplasm, 

 which become larger until the condition of "heat rigor" sets 

 in. Kiihne, in 1864, showed that in muscle cells, at least, there is 

 contained a proteid which becomes turbid through partial coag- 

 ulation at 40, and Halliburton 3 has found that in nearly all 

 tissues are globulins coagulating at from 45-50 ; it is prob- 

 able, therefore, that the granules formed in heated cells are 

 produced through coagulation of these proteids. The impor- 

 tance of this coagulation in determining death is not yet fully 

 established, but it would seem to be very great. Halliburton has 

 observed that in both muscles and nerves to which heat is applied, 

 contractions occur at various temperatures, corresponding exactly 

 with the temperatures at which the several varieties of the pro- 

 teids of the cell coagulate. Furthermore, Mott 4 has found that the 

 temperature that is immediately fatal to mammals (47) is 

 exactly the same as the coagulating temperature of the lowest 

 coagulating proteid of nerve-cells. This fact is undoubtedly of 



1 Literature, see Davenport, " Experimental Morphology," New York, 1897 J 

 Schmaus and Albrecht, Ergebnisse der Pathol., 1896 (3, Abt. 1 ), 470. 



2 The adaptation of animal cells to high temperatures is an interesting topic, 

 especially in view of such results as those of Dallinger, who, by raising the 

 temperature gradually during several years, caused flagellata with a normal 

 maximum of about 21-23 to become capable of living at 70 (see Daven- 

 port). 



1 " Biochemistry of Muscle and Nerve, " Phila., 1904. 

 * Quoted by Halliburton. 



