49-2 



NATURE 



[September 15, T904 



In prepared soil in pots the results fully surpassed those 

 obtained both with nitrate of soda and sulphate of ammonia, 

 the less satisfactory yields obtained in the field being perhaps 

 due to the organic acids inducing the formation of a certain 

 amount of the poisonous dicyandiamide. 



So far as one may judge from the information available, 

 it would appear that agriculture will not have long to wait 

 until it is placed in the possession of new supplies of that 

 most powerful agent of production, nitrogen, and Sir William 

 Crookes will see the fulfilment of his prediction that " the 

 future can take care of itself." 



N'ltYagin. 



A few years ago much interest was excited in this and 

 other countries by the announcement that the scientific dis- 

 coveries of Hellriegel and Wilfarth had received commercial 

 application, and that the organisms of the nodules of the 

 roots of Leguniinosa2 could be purchased in a form con- 

 venient for artificial inoculation. The specific cultures 

 placed upon the market were largely tested practically and 

 experimentally, but the results were such as to convince 

 even the patentees, Nobbe and Hiltner, that the problem 

 which promised so much for agriculture had not been satis- 

 factorily solved. Since that time, however, investigators 

 have not been idle, and the present position of the subject 

 is lO be found in a recent Report by Hiltner and Stbrmer.' 



It was early recognised that the organisms (bacteria) 

 which inhabited the root-nodules of the various species of 

 LeguminosfE were not all alike, and that, in fact, they 

 showed marked physiological if not morphological distinc- 

 tions. Any particular species of leguminous plant is found 

 to resist more or less successfully the attempt of these various 

 organisms to effect an entrance into its root-hairs, and 

 according to the power of the organism to gain access, and 

 to establish colonies, so is the particular plant benefited and 

 the stock of fi.xed nitrogen increased. This power of adapt- 

 ability of the organism is designated its "virulence," a 

 term, however, which is perhaps hardly suited to our English 

 mode of expression, though it may for the present be re- 

 tained. It has been found that organisms of what is called 

 " high virulence " are capable of entering with ease the 

 root-hairs of vigorous plants at an early stage of their 

 growth, and of inducing the formation of nodules that are 

 large, numerous, and placed high up on the roots. 

 Organisms of low virulence, on the other hand, can only 

 enter plants of feebler growth, or plants that have passed 

 the most vigorous stage of vouth, so that the nodules, in 

 this case, are small and scarce, and distributed, for the most 

 part, near the ends of the roots. The practical object, there- 

 fore, would appear to be the breeding of strains or varieties 

 of organisms of high virulence, adapted to the symbiotic 

 requirements of the various important species of farm and 

 garden leguminous crops. 



The nitragin put on the market a few years ago was 

 used in two ways, being either applied directly to the fields, 

 or mixed with water and brought into contact with the seed 

 before sowing. Under the former method of procedure an 

 increase of crop was obtained only when the nitragin was 

 used on land containing much humus. The explanation 

 given for failure under other conditions was that the bacteria 

 artificially introduced perished for want of food before the 

 leguminous seed germinated and produced plants. 



Failure of the nitragin to effect an improvement in the 

 crop when it was sprinkled on the seed is now believed to 

 be due to the action of secretions produced by the seed in 

 the early stages of germination. These secretions are found 

 to be rich in salts of potash, and when brought into contact 

 with the bacteria in question they induce changes allied to 

 plasmolysis, and these changes are subsequently followed 

 by death. This difficulty was found to be got over by 

 nioistening the seed and allowing it to sprout before the 

 nitragin was applied ; but manifestly such a procedure would 

 always be difficult, and often impossible, to carry out in 

 priictice. The object, however, would appear to have been 

 gained in another way, namely, by cultivating the bacteria 

 in a medium that imparts to them the necessary power of 

 resistance. Such nourishment may take various forms, but 

 that which gave the best results consisted of a mixture of 



Unt( 



Leguminosen und deren Jirreg' 

 Latui- u„d Forshvirtschaft ,t,ii 



ngen 



Wu 



IknBllchen de 

 Arhciten aiis ricr Biol. Aiteil. fu. 

 iimlheilaiimte, Ennd iii. Heft 3. 



NO. 1820, VOL. 70] 



skim milk, grape sugar and pepton, and it is in this medium 

 that the organisms of the nitragin now distributed are 

 cultivated. 



Early in the present year the new nitragin was being 

 offered free of cost to all members of the German Agri- 

 cultural .Society on the condition that it was used in accord- 

 ance with the directions that accompany it. In consequence 

 of the large demand the free offer was in April withdrawn, 

 but the substance may be purchased from Prof. Hiltner, of 

 Munich, in quantities suflicient to treat the seed of a half 

 to one acre at the price of one shilling. The United States 

 Department of Agriculture are so convinced of the practical 

 utility of the improved nitragin that they are distributing 

 large quantities to American farmers. In this way the 

 material will be thoroughly tried in two hemispheres under 

 practical conditions, and cibundant evidence should soon be 

 forthcoming as regards its effects. It is to be hoped that 

 British investigators will not be deterred by past disappoint- 

 ments from putting the new form of nitragin to the test. 



Improvement of Varieties of Crops. 



Speakirtg generally, the attention of agricultural investi- 

 gators during the past fifty years has been directed more 

 to manurial and similar problems than to the improvement 

 of the yield of crops through the agency of superior varieties. 

 This, it seems to me, is the outcome of the tradition that 

 agricultural science is based upon chemistry, using the term 

 in its old-fashioned and restricted sense, and as a consequence 

 farmers have looked principally to the chemical laboratory 

 for light and leading. It is true that much excellent work 

 has been accomplished from the botanical side, but this 

 has been performed rather by farmers, seedsmen, or 

 amateurs, than by trained botanists. But fortunately the 

 botanist is now getting his opportunity, and the possibilities- 

 before him are sufficiently attractive. 



Judging by the results that have been obtained, it would 

 appear that wide divergences as regards yield, nutritive 

 qualities, resistance to disease, and other important proper- 

 ties exist between varieties of the same plant-species ; so 

 much so, in fact, is this the case that attention to the 

 relationship between variety and locality would appear to 

 be one of the most important matters to which a farmer can 

 give consideration. But it has been found that new varieties, 

 are frequently unstable, reverting rather rapidly to an un- 

 satisfactory form, or displaying a lack of power of resistance 

 to disease. It therefore becomes necessary constantly to be 

 producing new varieties to take the place of those that are 

 worn out, and it seems reasonable to anticipate that the 

 professional botanist will take a much larger part in this- 

 work than has been the case in the past. 



Not only is the yield of a crop greatly influenced as regards- 

 quantity and quality by the variety of seed employed,' but, 

 as is well known to practical farmers, the local origin of 

 the same variety of seed has a marked influence on many 

 properties of plants (vigour, resistance to disease, and 

 resistance to frost, and to weather generally), and these 

 properties quickly react on the yield. In this country we 

 have a prejudice in favour of the seed of English-grown red 

 clover, Provence Lucerne, Scotch potatoes, Belgian flax, 

 Ayrshire ryegrass, pine and larch from Scotland, Norfollc 

 and Cambridge barley. Warp-land wheat, &c., and there 

 seems no reason to doubt that such preferences are based 

 upon sound experience. This subject would appear to be 

 one that is still full of interesting and important possibilities, 

 and last year I had the opportunity of seeing some striking 

 results in a new and unexpected direction. During the past 

 few years the .Austrian Experimental Forestry Station of 

 Mariabrunn has given much attention to the influence of 

 the local origin of the seed on the resulting trees, especially 

 the common spruce, and, although it is too early to pro- 

 nounce a final judgment on the results, these are already so 

 conspicuous as to warrant my placing some figures before 

 you.' 



In the autumn of i8g6 a supply of seed was obtained from 

 certain definite localities, the trees that yielded it being of 

 varying dimensions and situated at various altitudes. The 

 seed was sown in the spring of 1897 in the nursery attached 

 to the station, and, having been transplanted into lines, a 

 portion of the young trees are growing there now. Others. 



'ersammlung des Inlernat. Veibandts Forst- 

 lariabrunn," 1903, p. ,7. 



