CHAPTER V 

 THE DISCOVERY OF CHEMOSYNTHESIS 



WE have traced the gradual development of our know- 

 ledge of the formation of organic substance during the 

 latter part of the last century, and have seen how the 

 processes taking place under the influence of light have 

 been unravelled by the efforts of a long series of workers 

 in all countries. 



Towards the end of the century a very far-reaching 

 discovery was made, in some sense almost inadvertently ? 

 in connexion with a research which was directed in the 

 main to the elucidation of certain of the problems con- 

 nected with the supply of nitrogen. This was the deter- 

 mination of the fact that another process of formation of 

 organic substance from inorganic materials exists in nature, 

 carried out by certain plants, but without -the intervention 

 of the chlorophyll apparatus and without the necessity of 

 the access of light. 



The process is, of course, found to occur only to a limited 

 extent, and the power to initiate it is confined to certain 

 micro-organisms, some of which have been shown in an 

 earlier section to be concerned in the presentation of com- 

 bined nitrogen in suitable form to the green plant. 



Our information starts with observations made in 1886 

 upon the nitrifying bacteria, then attracting a good deal 

 of attention. Warington, as we have seen, found great 

 difficulty in cultivating them in the media ordinarily in 

 use, and Munro also noticed that they exhibited a decided 

 distaste for all kinds of organic nutriment. In the same 

 year Heraeus found he obtained very energetic growth when 



