November 25, 1915] 



NATURE 



357 



of contained water the respiration increases regularly 

 up to 25-30 per cent, loss, when it reached two or 

 tliree times the respiration of similar undried material. 

 i>t yond this point dryinjj; had no further effect until 

 5u^o per cent, of the water had been removed, after 

 which the respiration steadily diminished, not ceasing 

 entirely so long as any water remained in the material. 

 Prof. W. B. Bottomley gave the results of relative 

 determinations of growth-stimulating " auximones " 

 by means of the bacterial scum formed in their pre- 

 sence on crude nitrifying culture solutions. The rela- 

 tive amounts in fresh and rotted manure and bacterised 

 peat respectively were i, 5, and 250. The formation 

 of auximones during germination was demonstrated ; 

 excised embryos were found to flourish in culture solu- 

 tions only if auximones were added. Culture experi- 

 ments with Lcmna minor showed that the purer frac- 

 tion precipitated from extracts by silver nitrate stimu- 

 lates growth more than the cruder phosphotungstic 

 fraction. 



Other Papers. 



The only foreign guest of the section, Prof. Julius 

 McLeod, of Ghent, demonstrated the possibility, in 

 the case of certain mosses, of describing and deter- 

 mining species biometricall3\ Using the genus 

 Mnium, as an example, the maximum, mean, and 

 minimum values for the length, breadth, etc., of the 

 leaves on successive portions of the fertile stem up to 

 the longest leaf were tabulated. The results showed 

 that the correlation between these measurements was 

 characteristic of the species, so that by comparing the 

 length, breadth, etc., of, for instance, the longest leaf 

 of a given specimen with data for the longest leaves 

 of the various species, it could be identified. 



Dr. J. C. Willis put forward the view, based on 

 a statistical study of the flora of Ceylon and India, 

 that very local indigenous species are those of recent 

 origin, while species widely distributed on the main- 

 land as well, are those long established. He found 

 no evidence of the elimination of species by "natural 

 selection " ; most of the widely distributed species are 

 also common, few rare, while of the endemic species 

 the majority are rare. 



Dr. E. }. Salisbury described the influence of 

 coppicing on the ground flora of Oak-Hornbeam 

 woods on clay soils. Before coppicing, it comprises 

 chiefly perennial herbs with storage organs which 

 produce their leaves very early in the spring. After 

 coppicing, species from the edges of the wood and 

 paths invade the opened areas, accompanied by weeds 

 of cultivation with good dispersal mechanisms. Some 

 of the old occupants are enabled by the increased 

 light to flower. The soil becomes more acid and drier. 

 The gradual return of tlie ground flora to its original 

 condition as the undergrowth thickens was described. 



In addition to the contributions already mentioned, 

 Mrs. M. G. Thoday di-monstrated the structure of 

 seeds of Gnetitm gnemon. Miss E. M. Blackwell dealt 

 with the occurrence of stomata on hypogeal cotyledons, 

 and other smaller demonstrations were given. 



Reports. 

 Reports on the work of committees of the section 

 were submitted as follows : — By Prof. T. G. B. 

 Osborn, on the cutting of sections of Australian fossil 

 plants; and on Australian Cycadaceae; by Prof. A. J. 

 Ewart, on investigations of the influence of various 

 ttmospheric pressures upon geotropic and heliotropic 

 iiritabilitv and curvature ; by Mr. R. S. .'\damson, on 

 the vegetation of Ditcham Park, Hampshire; bv Prof. 

 R. H. Yapp, on the Cinchona Botanic Station in 

 Jamaica ; and by Mr. R. P. Gregory, on experimental 

 studies in the physiology of heredity. 

 NO. 2404, VOL. 96] 



AGRICULTURE AT THE BRITISH 

 ASSOCIATION. 



ALlL interest in agriculture centres at the present 

 time in the economic problems involved in the 

 desired increase of the scope and efficiency of British 

 farming as measured by its output of foodstuffs. It 

 was inevitable, therefore, that the programme of Sec- 

 tion M. this year should be largely devoted to the 

 consideration of the existing situation and of the 

 economic factors which govern the introduction of 

 changes in the direction of increased production. 



The inaugural address of Mr. Revv, apart from its 

 other merits, served to give the section at the very 

 outset an admirable risumd of the existing situation 

 as regards the share contributed by British agriculture 

 to the national food supplies, and more particularly 

 the extent to which it has assisted during the past 

 year in making good the lack of supplies from sources 

 cut off by the war that under normal conditions would 

 have furnished us with some portion of our food. He 

 was able to renew the assurance given by him three 

 years ago at Dundee that, even in normal times, the 

 share of British agriculture in the food supply of the 

 nation is more considerable than is commonly realised. 

 Further, he could demonstrate that this share has been 

 substantially increased during the first year of war, 

 whilst, thanks to the Navy, the total supplies which 

 have reached our shores have been actually rather 

 larger in time of war than in time of peace. 



After the address, reports upon the present situa- 

 tion and outlook with reference to supplies of manures 

 and feeding-stuffs were presented by Prof. Hendrick 

 and Mr. E. T. Hainan. Prof. Hendrick directed 

 attention to the difficulties that were likely to arise in 

 connection with the supplies of phosphatic manures, 

 especially "dissolved" manures, owing to the increased 

 cost of imported raw materials and the difiiculties of 

 distribution. The loss of supplies of potash manures 

 from Germany could be met only to a very slight 

 extent from other sources, but much might be done 

 to reduce existing waste of potash in the form of 

 loss of liquid manure. The exploitation of seaweed 

 as a source of potash and iodine was also worthy of 

 attention. In a later paper Prof. Hendrick quoted 

 numerous analyses of seaweeds, both Fucus and 

 Laminaria, which showed that the latter contain 

 appreciable quantities of potash, amounting in some 

 cases to fully 12 per cent, of the dry matter. 



Mr. Hainan dealt more particularly with the supply 

 of feeding-stuffs, and summarised the results of tests 

 made at different centres with materials new to the 

 British market, such as dried yeast and palm-nut 

 kernel cake. 



A further contribution to this day's programme was 

 made by Prof. Somerville, who gave the results of a 

 series of pot-culture experiments which demonstrated 

 clearly the accumulation of fertility in the grass-land 

 of five selected farms as a result of the application of 

 basic slag. , . , , , 



The second dav's programme furnished a natural 

 corollary to Mr.' Rew's address in the shape of a 

 discussion of various aspects of the present and future 

 agricultural situation as affected by the war. For 

 the purposes of this discussion Mr. T. H. Middleton, 

 Permanent Under-Secretary of the Board of 

 Agriculture and Fisheries, opened the day's pro- 

 gramme with an interesting comparison of the effici- 

 ency for the production of food of different svstems 

 of farming. Bv ingenious methods of computation he 

 was led to the conclusion that, whereas grazing at its 

 ' best produces probably not more per acre than sixty- 

 ' seven davs' supply of protein, or 140 days' total supply 

 j of energy for a man, and, at its worst, produces no 



