320 GENERAL PHYSIOLOGY 



hand, and death upon the other, are merely the remote end-stages 

 in this development, and are united to one another by an un- 

 interrupted series of intermediate stages. The two end- stages 

 may be easily and sharply distinguished, but it is impossible to 

 draw a sharp line at the place where life ceases and death begins. 

 Hence this transition from life to death is termed necrobiosis, a 

 word that was introduced into pathology by K. H. Schultz and 

 Virchow. Virchow ('71) distinguishes between necrobiosis and 

 necrosis by means of external characters, speaking of necrobiosis 

 when the original form of the part in question is completely 

 destroyed and done away with, and of necrosis when it is still 

 retained in death. But. however practicable this external dif- 

 ference may be in the judgment of gross relations, of whole organs 

 or tissues, it has little importance theoretically, for whether the 

 end-result assumes this or that form frequently depends upon 

 wholly accessory matters. If, e.g., a cell has a solid wall, its form 

 long remains, although the protoplasmic body may long since 

 have perished ; but if its protoplasm is naked, the cell usually disin- 

 tegrates into a formless mass of granules ; nevertheless, the essence 

 of the process that leads to death may be the same in the two 

 cases. Hence it seems advantageous to lay aside this distinction 

 and so to extend the conception of necrobiosis that it may include 

 also the so-called necrotic processes. There is then understood by 

 necrobiosis those processes that, beginning with an incurable lesion of 

 the noi*mal life, leads slowly or rapidly to unavoidable death. The 

 frequent synonymous conception of degeneration has the disadvan- 

 tage that it has more than one significance and is employed for 

 many very different phenomena. 



The phenomena of necrobiosis introduce a subject which, on 

 account of its enormous practical importance, has been developed 

 as an independent science and has assumed large proportions ;. 

 this is pathology, the science of diseases. The following considera- 

 tions will, therefore, largely pertain to this subject, and an 

 endeavour will be made to analyse the death-process. 



Since the cell is the proper seat of life, it must be the object, 

 of study in the investigation of necrobiosis as in that of vital 

 phenomena. The death of compound organisms with their widely 

 differentiated organs and tissues depends simply upon the death 

 of the individual cells composing the cell-community. But the 

 phenomena that lead to death are very different in the individual 

 forms of cells. This depends partly upon the condition of the 

 living substance that characterises each form, and partly upon the 

 nature of the causes that lead to the death of the cell. It is, 

 therefore, evident that necrobiotic phenomena must be very 

 manifold. Nevertheless, they can be brought into two great 

 groups, which differ fundamentally from one another. In one 

 group the normal vital processes drop out gradually without under- 



