324 



GENERAL PHYSIOLOGY 



very simple manner. The nuclear membrane disappears, the 

 contents of the nucleus mix with the protoplasm, the chromatic 

 substance becomes gradually paler, until the whole leucocyte 

 becomes a homogeneous mass, which disintegrates with swelling 

 and formation of vacuoles (Fig. 137). 



To the atrophies may be added a series of death-processes, 

 which, although they have little similarity to one another, are 

 grouped in pathology under the common name of necroses. 1 In 

 general they have a more acute course than atrophies. 



Among the various necrotic processes several important forms 

 can be distinguished, which are characterised by definite peculi- 

 arities. One of these is mummification or dry gangrene. In this 



the tissue-cells shrink into solid, 

 leather-like masses on account of 

 a loss of liquid, so that when the 

 process has reached its end the 

 tissues appear dry, hard and 

 friable. Mummification occurs 

 normally in the drying-up of the 

 remnant of the umbilical cord of 

 the new-born child; in patho- 

 logical conditions, as after burning 

 or freezing the ends of the fingers 

 and of the toes ; particularly in 

 old age ; and also in the drying- 

 up of embryos that develop in the 

 abdominal cavity of the animal 

 or the human being instead of in 

 the uterus and, being incapable 

 of birth, die within the body of 

 the mother. Such embryos as- 

 sume gradually a hard, mummy- 

 like consistency, because the liquid 

 contained in them is absorbed by 

 the mother's body. A second important form of necrosis is coagula- 

 tion-necrosis, first investigated in detail by Weigert (75, 77, 78, '80), 

 which consists in the coagulation of the proteids of the tissue-cells 

 in question. With the coagulation-necroses may be classed the 

 usual rigor of dying muscles, which along with gradual contraction 

 transforms the muscles into stiff organs and causes the rigidity 

 of corpses. Weigert himself does not allow this classification, 

 regarding the co-operation of lymph as essential to the occurrence 

 of the coagulation-necrosis. But the process in rigor mortis, 

 although transitory, is the same in principle ; for the myosin, the 

 proteid that is characteristic of and contained in solution in the 

 living muscle, coagulates in dying and thus produces the stiffen- 

 1 Of. Cohnheim ('77 '80) and Ziegier ('95). 



FIG. 138. Waxy degeneration of muscle in 

 typhoid fever, a, Normal cross-striated 



nective tissue. (After ziegier.) 



