THE GENERAL CONDITIONS OF LIFE 



327 



course of a few hours, the time varying according to the thickness 

 and size of the piece, there is seen in place of the transparent 

 protoplasmic mass, a collection of small granules and globules, 

 between which lie isolated, larger, round droplets of hyaline proto- 

 plasm (Fig. 141, ///, D, &), and sometimes one or more faint, 

 round, transparent bubbles (Fig. 141, ///, D, a\ all being loosely 

 held together by a very delicate viscous mass. There is no doubt 

 that this collection of granules and globules has arisen by the 

 transformation of a mass of living substance that originally 

 was wholly clear. In the study of this process with stronger 

 magnifying powers an interesting fact appears. In the normal 

 life of the cell a characteristic difference in the behaviour of the 

 protoplasm of the pseudopodia of the Hyalopus during the phase 

 of expansion and that of contraction may be recognised. While 

 during the former, i.e., extension, 

 the protoplasm appears completely 

 homogeneous, during the latter it 

 assumes the typical alveolar struc- 

 ture of Btitschli, 1 and, if the con- 

 traction becomes very strong, as after 

 stimulation, the protoplasm becomes 

 uneven and knobbed upon the sur- 

 face (Fig. 141, Fand VI). Exactly 

 the same phenomenon appears in 

 the development of granular disin- 

 tegration. The protoplasm begins 

 to assume the alveolar structure ; 

 then the alveolar walls are gradually 

 drawn together in uneven and 

 lumpy masses ; they burst here and 

 there, and become rounded off into 

 small globules and droplets ; these are held together in a loose, 

 granular heap merely by the viscous liquid of the burst vacuoles, 

 which frequently flows together into a large, viscous drop (Fig. 

 141, IV). Thus, granular disintegration depends upon a supra- 

 maximal contraction. 



This fact is of great interest, for, if the histolytic processes 

 be followed comparatively in different cells, it is found to be 

 a common law that all elements, the contractility of which can 

 be clearly expressed, arid hence especially all naked protoplasmic 

 masses, such as Rhizopoda, protoplasmic drops from tissue-cells, 

 contractile fibrillse, muscle-fibres, etc., without exception die in 

 the phase of contraction. Amoeba and leucocytes (Fig. 142) in 

 necrobiosis, as in every contraction, assume a more or less com- 

 pletely spherical form (Fig. 142, B). Khizopoda possessing long 



1 Cf. p. 86. 



FIG. 140. Granular disintegration. 7, 

 Piece of a Spirostomumdisin 



from the wounded place. //, Pelomyxa 

 disintegrating as the result of over- 

 stimulation upon one side. 



