PROTOPLASM. 25 



of the transparent portions of the cell body, in which the 

 granules lie imbedded. This, the really working part of the 

 cell, is known as the cell protoplasm. The role of the 

 nucleus and granules so often present is not yet well 

 understood; possibly the granules in many cases represent 

 incompletely assimilated food. 



What the actual chemical constitution of protoplasm is 

 we do not know, but it is one of great complexity. All 

 methods of chemical analysis destroy it, and what we analyze 

 is not protoplasm, which is always alive which is a form 

 of matter endowed with those properties which we call 

 vital but a mixture of the products of its decomposition 

 when it ceases to live. Such a mixture is often called dead 

 protoplasm, but the phrase is objectionable as implying a 

 contradiction. Wherever there is protoplasm there is life, 

 and wherever we meet with life we find protoplasm, so that 

 it has been called the " physical basis of life." The name 

 protoplasm, is, moreover, to be regarded as a general term 

 'or a number of closely allied substances agreeing with one 

 another chemically in main points, as the proteids do, but 

 differing in minor details, in consequence of which one cell 

 differs slightly from another in faculty. On proximate 

 analysis every mass of protoplasm is found to contain much 

 water and a certain amount of mineral salts; the water 

 being in part constituent or entering'into the structure of 

 the molecules of protoplasm, and in part probably deposited 

 in layers between them. Of organic constituents proto- 

 plasm always yields one or more proteids, some fats, and 

 some starchy or saccharine body. So that the original 

 protoplasm is probably to be regarded as containing chemi- 

 cal " residues" of proteids, fats, and carbohydrates, com- 

 bined with salts and water. 



The Fundamental Physiological Properties. All living 

 animals possess in greater or less degree the properties con- 

 sidered in this chapter; and since the science of physiology 

 is virtually concerned with considering how these proper- 

 ties are acquired, maintained, and manifested, and for 

 what ends they are employed, we may call them the funda- 

 mental physiological properties. 



