334 



NA TURE 



\August I, 1889 



a form in which it becom2S available to the chlorophyllaceous 

 plant ; much in the same way as has been observed by Gilbert 

 in the case of fairy-ring-;, where the fungus, so to speak, prepares 

 the nitrogenous nutriment for the grass. That the tubercules 

 that are nearly always present on the roots of leguminous plants 

 are in some way connected with the assimilation of nitrogen by 

 the plants is an hypothesis that is gaining ground. Much stu ly 

 has of late years been devoted to the morphology and functions 

 of these tubercules by, amongst others, Tschirch, Brunchorst, 

 Frank, VanTieghem, Lundstrom, and Marshall Ward ; and still 

 more recently by Breal, Beyerinck, and Prazmowski. It seems 

 almost certain that these tubercules contain micro-organisms, 

 which are the proximate cause of the excrescences, and these 

 may live in symbiosis with the legumes, and prepare their ni- 

 trogenous food possibly from free nitrogen. The tubercules 

 are richer in nitrogen than the roots themselves, ,and some 

 ■observers look upon them as being merely reservoirs of nitrogenous 

 nutriment, not as manufactories. Beyerinck (i5t'/a«. Zeitimg, 1888) 

 has obtained and cultivated an organism which he calls Bacillus 

 radicicola, from these tubercules, and studied some of its reac- 

 tions. It seems very probable that further study of these tubercules 

 of the Leguminosoe may put us on the right track for solving the 

 mysteries of the nitrogenous nutrition of this order of plants. 



In a postscript to the memoir the authors state that they have 

 started some experiments with leguminous plants much on the 

 same lines as those of Ilellriegel and Wilfarth. The results 

 •of these experiments will be looked forward to with very great 

 interest. 



This memoir is a most welcome and solid contribution to a 

 most important problem. It is quite obvious that the last word 

 onjthe subject has not been said, and probably very much more 

 work must be done before it is. The authors, from their own 

 labours and thought on the subject, continued through so many 

 years, are well able to criticize the work of others, and this they 

 have here done, as far as most of the important papers published 

 up to date are concerned, in an able and frank manner. If 

 leguminous plants are able to avail themselves of the free nitrogen 

 of the air, or if soils are able, through the agency of microbes or 

 in other ways, to fix free nitrogen, the exact conditions necessary 

 for the accomplishment of these ends is not yet known. The 

 conditions of risk and exposure to accidental sources of nitrogen- 

 gain in small experiments in the open air are very great, and 

 experiments made under such conditions require very careful 

 verification. Also the methods of nitrogen determination used 

 should be subjected to rigorous investigation and control, as also 

 the methods of taking the samples used in analysis, which in the 

 ■case of a complicated body like a soil presents great difficulty in 

 obtaining a perfectly homogeneous mixture. The exact limits of 

 experimental error in the various determinations want investi- 

 gation. The subject, from its important practical bearings, is 

 worthy the attention of a scientific commission who could give 

 undistracted attention to it. E. K. 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE. 



Oxford. — An examination will be held at Queen's College, 

 in the first week of October, to fill up at least two open Classical 

 Scholarships for candidates proposing to commence residence 

 this October, and one open Scholarship in Natural Science 

 (Chemistry and Physics) for candidates proposing to commence 

 residence in October 1890. 



Classical candidates must not have exceeded nineteen years, 

 and Natural Science candidates eighteen years, on October 10, 

 1889. 



A further notice will be issued. 



SCIENTIFIC SERIALS. 



American Journal of Mathematics, vol. xi. No. 4 (Baltimore, 

 July 1889). — Prof. Cayley opens the number with a resumption 

 of his memoir on the surfaces with plane or spherical curves of 

 curvature (pp. 293-306). — The circular cubic with double focus 

 •on itself is treated by Schroter and T>\irhge[Crelle, Bd. v.). Mr. 

 F. Morley, writing on the geometry of a nodal circular cubic 

 (pp. 307-16), gives a geometrical account, illustrated by figures, 

 of the case when the curve, in addition, is nodal. Some pro- 

 perties of the special case when the inflexion is at infinity are 

 given by Dr. Booth [Quarterly Journal, vol. iii.) in his discus- 

 sion of the logocyclic curve (cf. vol. i, of his "Collected Papers," 

 -cap. XXX.). — The next paper supplies a defect in MM. Briot and 



Bouquet's " Proprietes des /onctions definies par des equations 

 differentielles " {Journ. def Ecole Pol., cap. xxxvi. ) : it is entitled, 

 "On the Functions defined by Differential Equations, with an ex- 

 tension of the Puiseux polygon construction (see Journ. de Math, 

 pures et appliquees, \. 15) to these equations " (pp. 317-28), and is 

 written by Mr. H. B. Fine. — In the memoir " Sur les solutions sin- 

 gulieres des equations differentielles simultanees" (pp. 329-72), M, 

 Goursat extends results obtained by M. Darboux to simultaneous 

 differential equations and to equations of higher order. — The 

 number, and volume, concludes with a note by J. C. Fields, on 

 the expression of any differential coefficient of a function of 

 any number of variables by aid of the corresponding differential 

 coefficients of any « powers of the function, where n is the 

 order of the differential coefficient (pp. 388-96) — All these 

 papers are, of course, purely mathematical : there is a physical 

 paper (pp. 373-87) by Prof H, A. Rowland, entitled " Electro 

 magnetic Waves and Oscillations at the Surface of Conductors." 

 The calculations are founded on Maxwell's equations. " In these 

 equations occur two quantities, J and ;//, Maxwell has given the 

 reasons for rejecting ^, and has shown that neither J nor -if enter 

 into the theory of waves. In order, however, that there shall be 

 no propagation of free electricity in a non- conductor, the com- 

 ponents of the electric force must satisfy the equation of 

 continuity, and this leads to components of the vector potential 

 satisfying the same equation, and J = o therefore. I have 

 satisfied my.self that there is absolutely no loss of generality from 

 these changes." 



In the Nuovo Giornale Botanico Itallano for July, Sig. A. 

 Bottini has an interesting article on the structure of the olive, 

 especially on that of the several layers of tissue of which the 

 ripe fruit is composed. A disease to which the crop has been 

 recently liable he believes to have been erroneously attributed 

 to a parasitic fungus, Seploria oleaginea. — The greater part of this 

 number is occupied by the proceedings of the meeting of the 

 Botanical Society of Italy held in Florence. — Prof. Arcangeli 

 gives an account of a series of experiments on the amount of heat 

 due to the respiration of fungi. The greatest elevation of tem- 

 perature he finds to amount to l°"25 C. in the case of Lepiola 

 excoriata. In all cases the elevation of temperature is most con- 

 spicuous about midday, or early in the afternoon. — The colouring- 

 matter of the cones of Abies excelsa is stated by Sig. L. Macchiati 

 to be due to a mixture of three distinct substances, two of them 

 crystallizable, accompanied by a waxy substance. 



Das Wetter for July contains : — (i) The second part of an ex- 

 planatory discussion, by Dr. Wagner, of the recently published 

 mstructions for the observers of the Prussian Meteorological 

 Institute. The points referred to relate especially to rainfall and 

 thunderstorm observations. The author refers to the variability 

 of rainfall values both as regards time and place, and to the 

 necessity of stations near each other, to explain the irregularities 

 of the yearly amounts. It is only since 1887 that such a system 

 has been established in North Germany, where it is proposed to 

 raise the number of stations to 2000, which will then only give 

 one for about 77 square miles. The hours of observation are 

 also discussed, the result being that the usual morning observa- 

 tion cannot be altered ; but the instructions direct that the 

 rainfall should be set down to the day upon which it is observed ; 

 this has generally been done in Prussia, whereas in other 

 countries it is put down to the previous day. The author refers 

 to the importance of the measurement of rain during th e passage 

 of thunderstorms, and also to the advantage to be derived from 

 the more general use, at stations of the second and third order, 

 of simple registering barometers and thermometers, siinilar to 

 those of Richard Freres. — (2) A criticism of Herr Falb's weather 

 predictions taken from an article in the Gdttingen Zeitung. M. 

 Falb bases his theory on the influence of the sun and moon upon 

 the interior of the earth, and upon the surrounding media of air 

 and water, and calculates certain "critical days" from the 

 relative positions of these bodies. The author of the article 

 has checked the predictions sent to the German agricultural 

 Press since April 12, and points out that although the weather 

 of May has been unusually warin, no mention of the fact was 

 contained in the predictions, and concludes with the remark that 

 a theory which shows such little success, as in the comparison in 

 question, is useless to the agriculturist.— (3) A description, by 

 Dr. Wagner, of the new popular Observatory, " Urania," 

 opened on July 3, in Berlin, on the site of the Exhibition 

 buildings. It contains a large equatorial, over 16 feet in length, 

 with a lens of about \2\ inches in diameter, a large number of 

 instruments and microscopes, and a spacious lecture theatre. 



