August 12, 1920] 



NATURE 



761 



urobable, that the micelle carries, cond<^nsed on its 



irface, not only a considerable proportion of the 



olvont, but also much of the undissociated solute. 



in reference to the j^eneral aspects of this work, two 



(omnients may be made. In the first place. Prof. 



\UBain, in attempting to determine the real character 



t soap solutions, has tackled one of the big out- 



inding problems that called most urgently for a clear 



)lution ; the six years which he has devoted to this 



work have therefore been used far more advan- 



tageouslv than in solving the hosts of minor prob- 



'• ms which appeal so strongfy to workers who are 



xious for immediate publication of results. In the 



lond place, the elucidation of the nature of soap 



solutions bv the theory of the ionic micelle is perhaps 



the biggest advance ' that has been made in the 



rheorv of electrolvtic dissociation since the early work 



of Arrhenius and van't Hoff. Other workers, 



ospeciallv in phvsiology, have made use of similar 



ideas, but in no previous case has the experimental 



evidence been so "complete or the theory established 



on so firm a basis as in the case of the soap solutions 



investigated in the Bristol laboratory. T. M. L. 



Plant Culture in Denmark. 



IN Denmark during the past twenty years there 

 have been great advances in the development of 

 the various branches of plant culture. The organisa- 

 tion and aims of this work are described by Prof 

 F. Kolpin Ravn in a recent number of the Scottish 

 Journal of Agriculture (vol. iii.. No. 2, April, 1920). 

 The first Danish experiments on plant culture were 

 commenced in i860 by B. S. Jorgensen, who took 

 Rothamsted as his model. Later development fol- 

 lowed various lines, but one of the most fam.ni = 

 pioneers was P. Nielson, who in 1886 became director 

 of the first State experiment station, and laid 

 the foundation of the extensive State experimental 

 work carried on at the present day. In 1893 the root 

 experiments which had previously been instituted 

 by the Society for the Improvement of Cultivated 

 Plants were placed under the control of the State 

 exF>eriment stations, and in 1903 the same thing hap- 

 pened with the wheat and malt-barley experiments of 

 the Royal Agricultural Society.' 



During the closing years of the nineteenth century 

 various agricultural societies became keenly interested 

 in plant-culture experiments, and by means of special 

 committees on plant industry a large amount of useful 

 work has been "carried out. Since 1905 an increasing 

 number of field experiments have been started by the 

 "smallholders'" societies, the members of which have 

 taken up this experimental work with great en- 

 thusiasm. All this work is carried out either by the 

 State itself or by institutions with the aid of Govern- 

 ment subsidies, the State contributing annually about 

 25,oooZ. for the development of plant culture. There 

 are eleven State experiment stations, eight of which 

 specialise in agricultural problems and the other three 

 in horticultural problem's. Field experiments and 

 laboratory work are included, while various sub- 

 departments carry out investigations on weeds, on 

 plant diseases, and on chemical, physical, and bac- 

 teriological problems. The State stations deal with 

 those problems requiring lengthy and very accurate 

 Aperiments, while the agricultural societies conduct 



\j)eriments designed to throw light on matters of 

 ntual and of local interest. The majoritS- of these 

 experiments deal with the use of fertilisers, and hints 

 as to the final results appear in a very short time. 

 -Another section of experimental work is that of plant 

 breeding, which is practised both by public and by 

 private institutions. This work is supported by the 

 NO. 2650, VOL. 105] 



State experiment stations in that all novelties ap- 

 pearing on the market are accurately tested by variety 

 and strain experiments without regard to the person 

 or institution by whom they have been grown. In 

 this way a competition oj>en to all seed-growers and 

 plant-breeders is formed, and this excites great 

 interest, since the results of the experiments deter- 

 mine the market price of the seed. 



Prof. Ravn points out that although the work 

 appears to be very much scattered, yet the various 

 institutions keep in close touch with each other by 

 joint meetings, etc., when the general lines of work 

 are discussed and common methods decided upon. It 

 is thought that this type of organisation is most 

 favourable to the development of initiative and to the 

 proper testing of new ideas and prod»;cts. 



N' 



Short-period Meteorological Variations. 



O. 102 of the Publications of the Royal Nether- 

 lands Meteorological Institute contains Dr. 

 E. van Rijckevorsel's eleventh communication on the 

 subject of secondary maxima and minima. The 

 author maintains that if sufBcient years be taken to 

 mask the long-period variations, and mean values for 

 an element such as temperature or barometric pres- 

 sure be set down for each day in the year, the result- 

 ing figures for any station will show a series of waves 

 of an average period of between ten and eleven days, 

 so that thirty-five maxima appear in the annual curve. 



The present contribution is devoted principally to a 

 comparison of the barometer values for thirty-three 

 stations from periods varying- from forty-three years 

 at Haparanda to only four years at Honolulu and St. 

 Vincent, with those obtained in the long series of 

 seventy-two years (183S to 1909) at Christiania. The 

 Christiania data are analysed more thoroughly, as the 

 whole series is divided into two thirty-six-year periods 

 A and B ; and also the first twenty-four years of A, 

 the last twelve years of B, and the first six years of B 

 are treated separately. Moreover, the data from 

 Christiania, Nertchinsk, and Innsbruck have been 

 specially examined, the means from an equal number 

 of years of maximum and minimum sun-spots having 

 been taken for each of the three stations. Innsbruck 

 is not one of the thirtv-three stations, which are them- 

 selves grouped according to latitude, the mean latitude 

 of the groups being 67°, 52°, 42°, and 21° respectively. 

 They are fairly well distributed in longitude. Dia- 

 grams are given of twelve pulsations, the groups 

 being separated and the stations in each group 

 arranged in order of longitude, and an attempt is 

 made to indicate a sort of systematic variation in the 

 agreement between the several curves. 



A final diagram gives apparently ideal curves of 

 temperature and pressure through the year, showing 

 the subsidiarv period onlv affected by some annual 

 variation which flattens the waves at the equinoxes, 

 comnared with actual values from fifteen years' data 

 at Buchar'-st. Dr. van Riickovorsel has devoted him- 

 self for manv vears to this particular investigation, 

 but it does not seem to have enlisted much supnort 

 UD to the nresent time. W. W. B. 



University and Educational Intelligence. 



Cambridge.— Prof. S. J. Hickson, of Manchester, 

 has been elected an honorary fellow^ of Downing 

 College. Mr. .\. J. Berry has been re-elected to a 

 fellowship. 



Glasgow. — Dr. .\. J. Ballantyne has been appointed 

 lecturer in ophthalmology in succession to Dr. M. 

 Ramsav. 



