326 GENERAL PHYSIOLOGY 



mena. Not rarely, different forms of necrosis occur combined, 

 and they become complicated especially by secondary factors, 

 such as putrefaction. The latter is the case with moist gangrene, 

 decay, etc., all of which are produced by the action of putrefactive 

 bacteria upon necrobiotic tissue, and some of which represent post- 

 mortem phenomena. Further, certain other forms of necrosis 

 have been more or less identified by pathology, but these patho- 

 logical classes are distinguished much more by the macroscopic 

 phenomena of the end-result than by the microscopic events in 

 the cell itself. The former naturally depend upon various kinds 

 of accessory circumstances that are not immediately conditioned 

 by the pure phenomena of cell-death. 



Finally, one more series of phenomena may be added to the at- 

 rophies and necroses ; these accompany the death of cells living in 

 aqueous media and are wide-spread among organisms ; they are the 

 phenomena of granular disintegration. 1 The one thing held in 

 common by all kinds of granular disintegration is that at the end 

 of the process the cell in question forms a more or less loosely 

 coherent mass of individual granules. 



Granular disintegration can be observed most easily in many In- 

 fusoria, when their protoplasm is especially rich in water. This is 

 the case in the large, cylindrical Spirostomum ambiguum which 

 has a soft, superficial layer of exoplasm. If such Infusoria be wounded 

 by being cut into two pieces under the microscope, it happens 

 very frequently that the pieces disintegrate away regularly from 

 the surface of the wound. Death can be followed by the eye, and 

 its course resembles that of a spark that passes over a fuse and 

 leaves behind it merely a loose mass of ashes. It creeps over the 

 whole body, seizing upon particle after particle, surprising cilium 

 after cilium in normal activity, and forcing them directly from 

 active life into a standstill, until that which a moment before 

 was in active motion is changed into a dead mass of granules 

 (Fig. 140). 



These very acute cases in infusorian cells, which interest every 

 observer who sees them for the first time, are not well-adapted 

 to a study of the more delicate protoplasmic processes, since, 

 with the protoplasm already very granular, it is difficult to 

 decide how far the granular material of the disintegrating 

 masses consists of the preformed granules, and how far it is 

 formed directly as such by the process of death. In this respect 

 many Rhizopoda, such as the marine Hyalopus Dujardinii (Fig. 

 141, I), which are completely hyaline and absolutely free from 

 granules, are extraordinarily suitable. If one of the smooth, clear 

 pseudopodia be cut off by a knife under the microscope, it begins 

 gradually to undergo granular disintegration from the place where 

 it was cut (Fig. 141, // and III}. Then, either very soon or in the 

 1 Of. Verworn ('96, 1). 



