was shortly afterwards confirmed by others, especially by Wino- 

 gradsky,:}: who was then working in Pasteur's laboratory in 

 i j aris. The bacterium thus isolated and bred by Frankland had so 

 long eluded detection because it does not and cannot feed and grow 

 upon the materials usually employed in bacteriological cultures, 

 broth, jelly, etc., that is on organic stuff. Winogradsky discovered 

 that it will grow and flourish only on mineral matter. A most 

 astounding discovery at that time, but having found out this, he had 

 no difficulty in keeping the bacterium alive and multiplying for 

 years. He was able to prove that his little organism played only a 

 part in the history. It converts ammonia into nitrous acid. It 

 was the organism that occurred in Warington's first culture. Having 

 started the work, others profited by this discovery, and Warington 

 with this hint found in 1891 in his second culture the second organ- 

 ism or link in the chain, namely the organism that converts the 

 nitrous arid into nitric acid.* And thus at last the whole process of 

 nitrification of the soil, that is the continued supply of nitrates, 

 became intelligible. It is due to two distinct forms of bacteria which 

 occur in enormous numbers in the soil, anything from ten millions 

 to forty millions per gramme of soil. So that in spite of the constant 

 removal of the nitrates from the soil by plants bacteria are as 

 constantly producing them. 



Yet these facts which to-day are known to every elementary student 

 of botany took many years of continuous, arduous, patient, and 

 ingenious research, carried on by several people, working at first 

 independently : Muntz 1877, Frankland 1890, Warington 1891 ; a 

 total of fifteen years of work, Warington himself devoting, on and 

 off amidst other work, thirteen years to the elucidation of this 

 problem. 



It must be borne in mind that this long piece of research work, 

 which is of as great importance to biology as to agriculture, was 

 carried out by men who were working from a purely scientific interest 

 in the problem. They found sufficient reward in the gradual over- 

 coming of the successive difficulties and in pushing forward the 

 discoveries step by step to a solution. 



Although we owe the commencement of our knowledge of these 

 bacteria to the experiments and observations of Englishmen, it is 

 only fair to mention that others put the matter on a firm footing by 

 confirming the experiments under varied conditions and extending 

 the work. For instance, Winogradsky, who did an immense amount 

 of work later, and was attacking the problem at about the same 

 time as Warington, gets most of the credit. Yet it is the discoverer, 

 the conceivor of new ideas, the initiator of new methods, who is 

 really deserving of most praise. 



Since Frankland' s discovery of the nitrous ferment in England it 

 has been found that the process is not carried out by the same 

 organism in all parts of the world. Different kinds of bacteria, 

 some of them motile, act as "nitrous ferment" in different parts of 



J Winogradsky, Annales Inst. Pasteur, 1890, 1891. 



* Warington, Journ. Chemical Soc., 1878, 1879, 1884, 1891. 



