[44] Sir John Lawes and Sir Henry Gilbert (Times, December 2, 1898), have pointed out that the addition of nitrates only would be of no permanent use to the wheat crop. They rely upon thorough tillage and proper rotation of crops as the means of improving the nitrogen value of the soil.
[45] Geddes, Nature, xxv., 1882.
[46] Sir Henry Gilbert, F.R.S., The Lawes Agricultural Trust Lectures, 1893, p. 129.
[47] Ibid., p. 140.
[48] This has been denied recently in the official report by the chemist of the Experimental Farm to the Minister of Agriculture at Ottawa (Report, 1896, p. 200).
[49] It has already been pointed out that the nitrifying bacteria, though able to live on organic matter, do not require such either for existence or for the performance of their function.
[50] Lehmann and Neumann, p. 305.
[51] The conditions requisite for an outbreak of enteric fever were, according to Pettenkofer, (a) a rapid fall (after a rise) in the ground water, (b) pollution of the soil with animal impurities, (c) a certain earth temperature, and lastly (d) a specific micro-organism in the soil. These four conditions have not, particularly in England, always been fulfilled preparatory to an epidemic of typhoid. Yet the observations necessary for these deductions were a definite step in advance of mere dampness of soil.
[52] Supplement to the Report of the Medical Officer of the Local Government Board, 1887, p. 7.
[53] Report of Medical Officer to Local Government Board, 1895–1896, Appendix.