THE BASIS OF LIFE 15 



rearrangements are effected by the chemist which do not 

 occur in nature. He has an almost infinite range of action. 

 Yet many of the rearrangements of matter and force which 

 are occurring in the dandelion on his window-sill (if the fumes 

 of sulphuretted hydrogen have not killed it) he is unable to 

 reproduce. It is largely a question of waste. Nature works 

 with greater precision than the chemist ; but the chemist could 

 do all that Nature does if he had but the same control of 

 force. 



We have spoken of the reactions which occur in protoplasm as 

 divisible into two great series the one ascending, constructive, 

 endothermal ; the other descending, destructive, exothermal. In 

 the one series energy is locked up ; in the other series it is set 

 free. Synthesis and analysis are names applied to the two series 

 respectively. Synthesis is characteristic of plants, although 

 analysis is also perpetually occurring. Plants fix carbon from 

 the air and liberate oxygen. They also respire, setting free 

 carbonic acid. Analysis is characteristic of animals, although 

 synthesis is not excluded. 



Of the chemical processes which occur in plants very little 

 is known. Few halting-places between raw materials and 

 finished products can be marked. The final products are 

 sugars and starches, oils, proteins, and a vast number of other 

 substances alkaloids, glucosides, etc. Condensation, de- 

 hydration, and deoxidation are the methods by which the syn- 

 thesis of these compounds is accomplished. These methods are 

 adopted simultaneously in varying degree. The large group of 

 bodies known as sugars and starches are, with few exceptions, 

 built on the C 6 H 6 model; in fruit sugar, C 6 H 12 6 , six atoms 

 of carbon are linked to one another and to six molecules of 

 water. The formula of starch is (C 6 H 10 5 ) n . Not only has 

 water been removed from the molecule, but an unknown 

 number of molecules have been linked together. This conden- 

 sation and dehydration is effected whenever sugar carried in 

 cell-sap is deposited as starch in seeds or tubers. These com- 

 pounds are hexatomic. The chemist pictures them as made 

 by the union in the first place of six atoms. As small drops 

 unite to form larger ones, so small molecules, under the direction 

 of the protoplasm of plants, close together. 



The reactions which characterize animal protoplasm are of 



