CHAPTER VI. 



THE CHEMISTRY OF LIVING MATTER 

 AND CELL DIVISION 



Organic Chemistry, although named after the organs of living 

 things, has come to be the study of carbon compounds. But as the three 

 great chemical groupings of a living organism consist of proteins, carbo- 

 hydrates and fats and all of these contain carbon, a large part of the 

 study of organic chemistry is still devoted to living matter. 



One of the great problems of biology is to solve the riddle of how 

 and where life originated. If the stars and planets surrounding our 

 globe were at one time masses of intensely heated matter no life could 

 have been sent from one planet to another. Still it is interesting to 

 know that the first elements appearing on a cooling star are the very 

 ones which go to make up proteins ; namely, carbon, oxygen, hydrogen, 

 nitrogen, and sulphur. 



It will be remembered that oxygen is the source of most of the en- 

 ergy of an organism, and that the cell is the unit of biology, this cell 

 being made up of various substances called protoplasm. 



If a substance is of the consistency of glue and non-crystalloid, 

 it is called a colloid. 



Colloids are contrasted with crystalloids, such as sugar, salt, urea, 

 etc., in fact, any of those substances which, when in solution, will pass 

 through a membrane. 



An emulsion is one fluid phase suspended in another. The fluids are 

 said to be in suspension. 



Most organic matter is colloidal and some biologists believe that a 

 colloid substance will ultimately be accepted as the biological unit in 

 place of the cell. 



Protoplasm, the substance of the entire cell, has somewhat the form 

 of foam, although it differs from foam in having the alveoli filled with 

 a thick liquid substance about the consistency of the white of an egg. 

 The alveoli which make up the foam-like protoplasm, although having 

 very thin walls, have walls thick enough so that diffusion is very slow 

 and the substance itself is different in the alveoli themselves and the 

 spaces between the alveoli. 



All protoplasm does not show such alveolar composition. With the 

 ultra-microscope much of the protoplasm appears as tiny particles. It 

 is, therefore, supposed that this homogeneous mass is colloid in charac- 

 ter, that is, consists of tiny granules which are suspended in a liquid 

 medium. As there isn't very much difference between a colloid and an 

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



