ORGANIC MATTER. 21 



conclusion which we before drew from first principles, that 

 this great unlikeness among the combined units must facili- 

 tate differentiations. 



§ 8. A portion of organic matter in a state to exhibit 

 those phenomena which the biologist deals with, is, however, 

 something far more complex than the separate organic mat- 

 ters we have been studying; since a portion of organic matter 

 in its integrity, contains several of these. 



In the first place no one of those colloids which make up 

 the mass of a living body, appears capable of carrying on 

 vital changes by itself: it is always associated with other 

 colloids. A portion of animal-tissue, however minute, almost 

 always contains more than one form of protein-substance: 

 different chemical modifications of albumen and gelatine are 

 present together, as well as, probably, a soluble and insoluble 

 modification of each; and there is usually more or less of 

 fatty matter. In a single vegetal cell, the minute quantity 

 of nitrogenous colloid present, is imbedded in colloids of the 

 non-nitrogenous class. And the microscope makes it at once 

 manifest^ that even the smallest and simplest organic forms 

 are not absolutely homogeneous. 



Further, we have to contemplate organic tissue, formed 

 of mingled colloids in both soluble and insoluble states, as 

 permeated throughout by crystalloids. Some of these crys- 

 talloids, as oxygen,* water, and perhaps certain salts, are 

 agents of decomposition; some, as the saccharine and fatty 

 matters, are probabl}'' materials for decomposition; and some, 

 as carbonic acid, water, urea, kreatine, and kreatinine, are 

 products of decomposition. Into the mass of mingled colloids, 

 mostly insoluble and where soluble of very low molecular 

 mobility or diffusive power, we have constantly passing, crys- 



* It will perhaps seem strange to class oxygen as a crystalloid. But inas- 

 much as the crystalloids are distinguished from the colloids by their atomic 

 simplicity, and inasmuch as sundry gases are reducible to a crystalline state, 

 we are justified in so classing it. 



