CHAPTER II. 



PROTOPLASM. 



SECTION I. CHEMICAL COMPOSITION OF PROTOPLASM. 



Protoplasm, the ' physical basis of life,' the granular trans- 

 parent viscous substance present in all living things, and 

 without which no life is possible, may be defined chemically as 

 an immensely complex compound, or mixture of compounds, 

 yielding on analysis l simpler chemical derivatives, which 

 may be classified under the folio wing heads : 



A. Proteids and albuminoids, containing carbon, hydro- 

 gen, oxygen, nitrogen, sulphur, phosphorus, and a variable 

 amount of ash. 



B. Amyloids or carbohydrates, containing the elements, 

 carbon, hydrogen, and oxygen. 



C. Fats, with a similar composition. 



D. Water in large quantity. 



E. Inorganic salts. 



F. Many bodies which are regarded as stages in the form- 

 ation or decomposition of protoplasm. 



All these substances are of the highest importance in a 

 study of biology, and we shall therefore devote some time 

 to their discussion. 



1 The process of analysis consists in (i) desiccation, i.e. drying 

 without combuslion, removing all volatile matters, and leaving only 

 non-volatile substances ; (2) combustion or calcination, which by 

 oxidation, dissociation, &c., removes all combustible bodies and leaves 

 a mineral, incombustible ash. 



