CHAPTER II 



THE CHARACTERISTICS OF LIVING ORGANISMS 



CERTAIN of these have already been referred 

 to. We may now consider some of the 

 characteristics of living beings more fully. 



8. Physical structure. No living matter 

 ever assumes a crystalline form, but crystals 

 may be imbedded in it. Living matter is 

 always soft, jelly-like, diffluent, readily per- 

 meated by water, oxygen, and the crystalloids. 

 It is matter in a colloidal state, which, as it 

 permits of the free play of molecular inter- 

 changes, has been termed a dynamical state 

 of matter. The colloidal shape is not, however, 

 peculiar to living matter, as it is shown by 

 certain conditions of silicic acid, peroxide of 

 iron, etc. The firmer portions of living matter 

 are always soft ; they readily absorb water 

 by imbibition. It has been supposed that 

 living matter consists of still more minute 

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