102 



NATURE 



{June i, 1882 



roots of plants, it is necessarily greater in wet seasons 

 such as have been the rule for the last few years. 



We believe that Pasteur was the first to suggest, twenty 

 years ago, that the process of nitrification going on in 

 soils and waters might be due to the agency of an 

 organism ; but it was not until the last five years that the 

 researches of Schlosing and Miintz and of Warington 

 conclusively showed that this is the case and that the 

 oro-anism is a bacterium. This bacterium is present in 

 all fertile service soils and under the proper conditions of 

 temperature, moisture, supply of oxygen, and presence of 

 salifiable base is continually converting ammonia and 

 nitrogenous organic matter, which has passed the putre- 

 factive stage, into nitrates. That nitrates are the chief 

 form from which most crops and especially the cereals 

 assimilate their nitrogen is now admitted generally, even 

 by the few physiologists who still cling to the belief that 

 plants can assimilate free atmospheric nitrogen ; the very 

 great use of this nitrifying organism is thus apparent. It 

 may be remarked in passing that this Schizomycete is 

 able to effect a change in a mineral substance, ammonia, 

 causing its oxidation into nitric acid, all other knoivn 

 organised ferments being concerned in the transformation 

 of organic bodies, and this is an operation hitherto un- 

 suspected in the life of any Bacteria. 



Nitrification takes place in soils most rapidly in the hot 

 months of the year, and as a cereal crop assimilates 

 little or no nitrogen after June, but merely transfers that 

 already taken up and present in the roots, stems and leaves 

 to other organs, it follows that, on a cornfield, in the late 

 summer and the autumn months, nitrates will be formed 

 and, will, in the event of wet weather, be readily washed 

 out of the soil. 



Observations made during miny years at Rothamsted, 

 and recently published by Messrs. Lawes, Gilbert, and 

 Warington, 1 show the extent to which this loss of nitrates 

 may occur. They find that on land uncropped and un- 

 manured, that is, a bare fallow, during 4 years 1S78-1SS1, 

 nearly forty-two pounds of nitrogen per acre per annum, 

 equal to nearly two and a half hundredweight of ordinary 

 nitrate of soda, was lost by drainage. They also estimate 

 that on land under continuous wheat cropping from ten 

 to twelve pounds of nitrogen per acre per annum was lost 

 by drainage from plots which received no nitrogenous 

 manure. When nitrogen is applied in the manure, con- 

 siderably larger quantities are lost in the drainage, and 

 this is exclusive of that diffused into the lower layers of 

 soil below the reach of plant roots, and of that which 

 may under certain condition; be lost by deduction to 

 elementary nitrogen. 



In an ordinary rotation the loss of nitrogen will be 

 considerably less than in these experiments, for crops 

 will often be growing for months after the cereal crop is 

 removed, and thus conserve the available nitrogen and 

 store it up for future use. It is however obvious, that, 

 with a bare fallow favouring the production of nitrate-, 

 followed by a wet season, a very considerable loss of 

 available nitrogen will occur through loss of nitrates, and 

 it becomes a matter for the farmer to consider whether it 

 is to his advantage, for the sake of cleaning his land, 

 to take the risk of this loss and supply the nitrogen at a 



1 Journal of the Royal Agricultural Society [2] xvli. an 1 xviii. : and 

 Journal 0/ Society 0/ Arts, April 7th. 1882. 



cost, in ammonia, salts, or Chili saltpetre, of nearly a 

 shilling per pound, or on the other hand, adopt some 

 system of cultivation and cropping by which much of the 

 loss may be obviated. On some soils the growth of an 

 autumn green crop would save most of the nitrates and 

 leave the land in fair condition for a succeeding crop ; 

 naturally the decision as to the advisability of such a 

 course must rest in each case with the individual farmer. 

 The Agricultural mind appears to always require a 

 panacea from the scientific man before it will accept his 

 results as of any use. At a recent meeting of the 

 Farmers' Club it was observed by a leading agriculturist, 

 that, although Mr. Lawes (now Sir J. B. Lawes) had 

 discovered the way in which nitrogen was lost, he had 

 not told the farmer how to retain the goods effects of 

 nitrogenous manures in adverse seasons. The discovery 

 of the manner in which the loss occurs is, however, an 

 immense step in the right direction, and moreover Lawes 

 and his colleagues have clearly shown that with a growing 

 crop on the land the loss is very greatly lessened. 



This bacterium of nitrification is but one of a great 

 number of the lower forms of life now engaging the at- 

 tention of 'scientific men, which are, or ought to be, of 

 immense interest to the scientific pursuit of agriculture. 

 The researches of Pasteur on the life history of Bacillus 

 of Anthrax, Aitken and Hamilton's investigations now 

 being conducted into the causes producing braxy and 

 louping ill ; and the study of the organisms concerned in 

 the changes which occur during the souring of milk and 

 the ripening of cheese are kindred studies bearing in a 

 direct manner on the daily practice of the farmer. Of 

 no less interest too is the biological work done by Kuhn 

 and Liebscher, which has traced the beet sickness to the 

 presence of a Nematode, while the investigations into 

 the life history of Hemileia vastatrix, the too well-known 

 coffee leaf disease, the Plasmidiophora, which is the 

 proximate cause of anbury in turnips, and the fungus 

 of potatoe disease, all point to the growing relation be- 

 tween the kindred sciences of biology and agriculture. 

 Illustrations might be multiplied almost indefinitely 

 but these are of sufficient importance to show that the 

 work of the microscopist and biologist has a wide and 

 deep influence, first of all on the practice of agriculture, 

 and through it on the comforts and the pockets of the 

 consumers at large. 



THE TRANSIT OF VENUS, 1S74 

 Account of Observations of the Transit of Venus, 1874, 

 December 8, made under the Authority of the British 

 Government. Edited by Sir George Biddell Airy t 

 K.C.B., Astronomer-Royal. 



THIS volume, recently published under the authority 

 of the Treasury, contains the official account of 

 observations of the last transit of Venus, by the five ex- 

 peditions organised at the public expense and the reduc- 

 tion of the observations. 



In an Introduction Sir George Airy briefly recapitulates 

 the various steps taken by himself with the view to the 

 efficient observation of this phenomenon, from his first 

 communication to the Royal Astronomical Society in 

 April, 1S57, " On the means which will be available for 

 correcting the measure of the sun's distance in the next 



