322 



GENERAL PHYSIOLOGY 



soon ; the chromatic substance and the nuclear membrane gradu- 

 ally shrink together and disintegrate into single fragments, which 

 likewise are finally dissolved. The muscle-fibres, though in other 

 respects very different, behave similarly. The individual fibrillse 

 swell and become cemented to one another. At the same time 



Fig. 135. — Histolysis of muscle-fibres in the tail of tlie larva of the-frog. (After Looss.) 



the isotropic and the anisotropic substances begin to mingle to- 

 gether, so that the cross-striation gradually disappears. The 

 double refraction of the anisotropic disks also fades away. At the 

 same time the fibres disintegrate into small round fragments, 

 which finally undergo solution (Fig. 135). The processes of 

 histolysis go on in a wholly analogous manner in most other cases, 

 e.g., in the degeneration of the larval organs of insects, the muscles 

 of the salmon, and the thymus-glands of human beings. But from 

 the investigations of Metschnikoff ('83), Kowalevsky ('85, '87), and 

 others, it appears that in many insects, especially in the fly-larva, 

 where the degeneration of the larval tissue proceeds uncommonly 



Fig. 136. — Fragments of muacle-iibres in the metamorphosis of the fly-larva, destroyed by 

 leucocytes. The darker, granular cells are the leucocytes. (After Kowalevsky.) 



rapidly, the histolysis is performed chiefly by the leucocytes, which 

 as phagocytes devour the tissue-cells that have not yet disintegrated 

 (Fig. 136). It must be supposed that here also the inauguration 

 of histolysis proceeds from the tissue-cells themselves, and that the 

 leucocytes devour the cells that are already beginning to atrophy. 



