March 19, 1908] 



NA TURE 



477 



pared with pollen-grains of cultivated potatoes, the former 

 being elliptical and the latter very irregular in form. 

 Siolannm ctuberostim is the only wild type of which the 

 seedlings have not reproduced the typical form, but have, 

 on the other hand, given precisely the same variation in 

 habit of foliage, form, size, and colour of tuber, &c., as 

 is found in the seedlings from the cultivated potato. 

 During the twenty years of cultivation, no plant of 

 Solantim eiuberosiim has ever been noticed as affected by 

 the fungus Phytophthora iiifcstaiis, although during the 

 whole period it has been grown in close association with 

 potatoes which have suffered more or less from it year 

 after year. It is a fact that the potatoes originally intro- 

 duced into England or into Europe were certainly intro- 

 duced as cultivated potatoes, and not as wild types, and 

 also that it is at least doubtful whether in Chili, Peru, or 

 elsewhere, any specific type of tuber-bearing Solanum 

 (apart from Solatium etuberosum) can be found which will, 

 under cultivation, give plants at all like the potato of 

 commerce. — Life-histories and larval habits of the tiger- 

 beetles (Cicindelidae) : Dr. V. E. Shelford. The paper is 

 intended to be followed by a series in which the distribu- 

 tion, variation, effects of environment, and evolution of 

 rolour will be considered. Eleven races were studied, and 

 the results detailed from three or four thousand individuals 

 which had been reared to maturity ; the detailed account 

 of Cicindela purtiiirca is followed by a comparison of the 

 other races, and the paper concludes with a bibliography. 



March 5. — Lieut. -Col. Prain, F.R.S., vice-president, 

 in the chair. — .\ possible case of mimicry in the common 

 sole: Dr. A. T. Masterman. There are two species 

 of weever-fish, Trachimis draco and T. vipera, both 

 venomous, with the poison concentrated at the spines of 

 the first dorsal fin and the opercular spine. These fishes 

 bury themselves in the sand until only the top of its head, 

 with eyes, mouth, and dorsal fins are above the sand. The 

 dorsal fin is of intense black, and conspicuous amongst 

 the sand when protruded ; it has been suggested that this 

 may be regarded as a warning signal to the enemies of 

 these fishes. The right or upper pectoral fin of the 

 common sole (Solca vulgaris) is well developed, and the 

 upper half of that fin has a large, deep, black patch. It 

 also has the habit of concealing itself under the sand, and 

 the distribution of the weever-fishes and the common sole 

 :s almost the same. In the other species of sole the 

 pectoral fin is smaller, or almost wholly wanting. The 

 suggestion is that the common sole has adopted the habit 

 and coloration of the weever-fishes as a protective measure. 

 — The morphology of Stigmaria and of its appendages in 

 comparison with recent Lycopodiales : Prof. F. E. Weiss. 

 The discovery bv Binney of an organic connection between 

 Stigmaria and the base of Sigillaria did not settle definitely 

 the morphological value of the stigmarian axis. It might 

 still be regarded either as a large bifurcating toot bearing 

 lateral roots or as an underground stem (rhizome), in 

 which case its appendages might be adventitious roots 

 fScott) or leaves modified to serve absorptive purposes 

 ■Solms-Laubachl, or possibly both kinds of lateral organs 

 might be present (Renault). Some recent observations 

 have tended to re-open the discussion of the morphology 

 of the appendages, particularly the recognition of peri- 

 pheral " transfusion " tracheids in the stigmarian append- 

 ages and the presence of a parichnos-strand in these 

 organs. But though both have their counterpart in the 

 leaves of the Lepidodendr.aceje, the author only sees analogy 

 nnd not homology in these structures, and believes their 

 presence is due to the physiological requirements of the 

 organs In question. On the whole, it seems likely that 

 'hese problematical organs are lateral extensions of the 

 protocorm of a ]>rimitive member of the Lvcopodiales. 



Physical Society, Frhniary 28.— Dr. C. Chree, F.R.S., 

 president, in the chair. — The contact potential differences 

 determined by means of null solutions : S. \\'. J. Smith 

 and H. Moss. When a mercury jet breaks in the surface 

 of an elech'olyle tliere is an E.M.F. between the jet and 

 a still immersed mercury electrode. If the contact p.d. 

 between the still mercury and the solution is tt, , that 

 between the jet and the solution being ir,,, the observed 

 E.M.F. is Ep = ir,- IT,,. This E.M.F. is found to be equal 

 to the polarising E.M.F., E„, required to produce the 

 maximum surface-tension between mercurv and the electro- 



NO. 2003. VOL. 77] 



lyte. Since E ,„ = ir, - 7r„, , where tt,,, is the p.d. between the 

 Hg and the electrolyte when the surface-tension is a maxi- 

 mum, it follows that 7r,„ = -irj. A solution for which E^=:0 

 is called by Palmaer a " null solution." He found by trial 

 two solutions for which E,, = o. Although he concluded 

 that ir, = jr,, = o, without special assumptions, the only neces- 

 sary conclusion is ir, = ir,, = ir,„. The object of this paper is 

 to show that Palmaer 's deduction is wrong. If an experi- 

 mental method can be found of obtaining Irom any electro- 

 lyte MX a solution for which E,„ = o, then an indefinite 

 number of null solutions can be obtained. Such a method 

 consists in the addition to the electrolyte of a small quantity 

 of M,S. A number of null solutions were found, including, 

 one which gave results identical with those obtained by 

 Palmaer. — An experimental examination of Gibbs's theory 

 of surface concentration regarded as the basis of adsorp- 

 tion, and its application to the theory of dyeing : W. C. M. 

 Lewis. An experimental investigation of Gibbs's theory 

 of surface concentration. A particular form of the more 

 general equation is 



r = "- — 

 HI itc 



where r = the excess mass of solute per sq. cm. surface^ 

 f = the bulk concentration of the solution, T = the absolute 

 temperature, R = the gas constant, and (r = the surface- 

 tension. Assuming surface-tension effects to be the basis 

 of adsorption, measurements were made of the quantities 

 above. The material at the surface of which adsorptioa 

 took place consisted of a pure hydrocarbon oil. The 

 material adsorbed was bile-salt in aqueous solution. The 

 inlerfacial tension a was measured by the drop-pipette 

 method, r was measured in two ways :— (i) at the surface 

 of oil-drops of radius about i mm., and (2) at the surface 

 of drops of radius about 10-' mm., i.e. emulsion particles. 

 The general result was that the actual values found for 

 r exceeded the calculated hy about fifty times the latter^ 

 the conclusion being that there is a discrepancy of con- 

 siderable magnitude. 



Zoological Society, March 3.— Mr. G. A. Boulenger, 

 F.R.S., vice-president, in the chair. — A young female 

 Kordofan giraffe ; P. C. Mitchell. The author compared 

 the coloration of this specimen, born at the gardens, with 

 that of its parents and with that of a young female giraffe 

 from Nigeria, now living in the society's collection, and 

 stated that the evidence to be derived from the study of 

 this specimen strengthened the case for the distinctness 

 of the giraffes from l-iordofan and Nigeria.— A comparison, 

 of the neotropical species of Corallus, C. coofci't with 

 C. madagascarictisis, and on some points in the anatomy 

 of Corallus caninus : F. E. Beddai-d.— A new species ot 

 monkey of the genus Cercopithecus : R. I. Pocock. The 

 species differs from C. neglccliis principally in the .ibsence 

 of the black band across the head, in the reddish tinge of 

 the hairs beneath the callosities, and in the similarity in 

 colouring between the tail and the body. It is proposed. 

 to name this new monkey Cercopithecus earae. 



Entomological Society, March 4.— Mr. C. O. Waterhouse, 

 president, in the chair.— £x/iifci(s.—F. B. Jennings : 

 (a) A ■ specimen of the weevil Phyllobius macuhcorms. 

 Germ., retaining both the " false " mandibles, and 

 another in which one of them is intact, both from Enfield, 

 also a single example of P. urticae, De G., from Cheshunt 

 retaining one of these mandibles, the particuUir point of 

 interest in connection with the false mandibles m these 

 species being that thev are toothed in the centre; (b) a 

 remarkable specimen of the common Chrysomelid beetle. 

 5crmy/o halensis, L., from Deal, showing unusual colora- 

 tion of the elvtra, which are blue and coppery-red instead 

 of bright green; and (c), on behalf of Mr. C. J. Pool, a 

 specimen of Otiorrhynchus tenebricosus, Herbst, fronn 

 Newport, I.W., and of Barynotus obsciirus. F., from 

 Galway, Ireland, in the first of which both the pupat 

 mandibles were toothed, and in the second not. — H. St. J. 

 Donisthorpe : Otiorrhynchus sulcatus, Polydrusus seri- 

 ceus, and Osmius bohemanni with pupal mandibles. The 

 Otio'rrhvnchus was dug up in its pupa! cell at Oakham in 

 1895.— the Rev. G. Wheeler : X case containing speci- 

 mens of Melitffiid butterflies taken by him at Reazzinoin 

 Tessin near Bellinzona, which he had identified with 



