io Life and Health 



It must not be supposed that the various chemical elements, 

 as the proteids, the salts, the fats, etc., exist in the body in a 

 condition to be easily separated one from another. Thus, a 

 piece of muscle contains all the various organic compounds 

 just mentioned, but they are combined, and in different cases 

 the amounts vary. Again, fat may exist in the muscles even 

 though it is not visible to the naked eye, and a microscope 

 is required to show the minute fat droplets. 



THE MINUTE STRUCTURE OF THE TISSUES 



15. Protoplasm. The ultimate living substance of the 

 body is called protoplasm. 1 



This material basis of all living things, whether plants 

 or animals, is a mixture of various organic compounds, the 

 chief of which, in all cases, are proteids. 



16. Cells. When we carry back the analysis of an 

 organized body as far as we can, we find every part of it 

 made up of masses of protoplasm of various sizes and 



shapes. Such bodies are technically 

 named cells. The white blood cor- 

 puscle is a typical cell having a nu- 

 cleus and nucleoli. Every cell has the 

 power of appropriating nutrient mate- 

 rial, of dividing and subdividing so as 

 to form new masses like itself. When 

 not built into a tissue, it has the power 



f chan S in g its sha P e and f movin g 



from place to place, by means of the 



A, nucleus; B, nucleolus: ... . ".' 11 -, 



c, protoplasm. (Highly delicate projections, technically called 

 magnified.) processes, which it puts forth. 



1 The word " protoplasm " must not be misunderstood to mean a substance 

 of a definite chemical nature, or of an invariable morphological structure ; 

 it is applied to any part of a cell which shows the properties of life, and is 

 therefore only a convenient abbreviation for the phrase, " mass of living 

 matter." 



