Chemistry of Living Matter and Cell Division 95 



emulsion in this case, and as there are cases in which no alveoli can be 

 seen, it is possible that alveolar substance and interalveolar substance 

 may differ about as much or as slightly as a colloid and an emulsion. 



The early workers on the cell saw very thin fibers in the proto- 

 plasm, and established the "filar" or "reticular" theories of protoplasmic 

 structure. We now know that, if the alveoli are arranged in rows, the 

 liquid between the alveoli will appear like threads, although we have 

 not been able to find that these so-called fibers have any important 

 function. These theories, therefore, are not among the important bio- 

 logical problems of the present time. 



When cells are prepared and stained for study in the laboratory, 

 they have many granules distributed within them. These may be coagu- 

 lation products of the interalveolar protoplasm or, the cut ends of fibers 

 or cell inclusions of various kinds. 



The great mass of protoplasm is really an emulsion. The tiny 

 bubble-like particles, or alveoli, and the liquid in which these float are 

 called by the physical chemist "phases" of a "system." It can, therefore, 

 be understood that the various surface phenomena which interest the 

 physical chemist are to be found in the living cell, and any chemical 

 knowledge of this nature, which the student of the cell can obtain, will 

 stand him in good stead. Much of the activity of protoplasm can be 

 explained by a study of surface tension. 



It is to be borne in mind that protoplasm is never solid, although 

 solid particles may be, and most often are, included within its liquid or 

 semi-liquid mass. 



Protoplasm is made up of both organic and inorganic substances. 

 Organic. 



A. Always present. 

 Enzymes. 

 Non-enzymes. 



Carbohydrates, 

 Proteins, 

 Fats, 

 Lipoids, 

 Extractors, 



Intermediate products of metabolism. 

 B. Not always present. 

 Pigments, 

 Hormones, 



Aromatic compounds, 

 Toxic compounds. 1 

 The enzymes are continually attempting to produce an equilibrium 

 in the cells. They are chiefly protein in nature and speed up the chemical 



1 lt is, of course, to be understood that a substance is not toxic to the individual in the normal 

 state. For example the poisonous sting of a bee or the poison gland of a rattlesnake is not toxic to 

 the respective animal but to others. 



