682 



NATURE 



[February ig, 1920 



than one locality, and in the inter-Andean region 

 strongly folded fossiliferous beds of Bajocian age are 

 found beneath an unconformable Cretaceous series. 

 The batholitic core is shown to comprise at least three 

 distinct phases of plutonic intrusion, represented by 

 granodiorites, diorites, and adamellites. The volcanic 

 cones of the western Cordillera have given rise to 

 an extensive series of lavas and tuffs comparable with 

 the Mauri River series of Bolivia. Cretaceous lime- 

 stones here take the place of the red gypsiferous sand- 

 stones farther south, and are transgressive on to 

 Devonian rocks. The latter contain abundant fossils 

 of Lower Hamilton age. The post-Cretaceous line of 

 dioritic intrusion, formerly described as running 

 through Core Coro and Comanche, once more appears 

 on the line of section. The Pcrmo-Carboniferous 

 fauna of Bolivia has not been discovered in the dis- 

 trict here described. 



Optical Society, Februarv 12. — F. G. Smith : A ray 



plotter. Describes a novel instrument for the tracing 

 of a ray through a refracting surface. — J. W. French : 

 The surface laver of an optical polishing tool. Sug- 

 gests a glass laver on the polishing tool as an effective 

 cause of polishing. — Mrs. C. H. Griffiths: Diffraction 

 patterns in the presence of spherical aberrations. 

 Photographs in the various planes of the diffraction 

 pattern for an artificial star were taken and measured, 

 with spherical aberration of varying amounts present. 

 These photographs were examined afterwards with 

 the view of determining the relative intensities of 

 light in the different zones of the ring interference and 

 diffraction patterns both at the focus and otherwise. 



Dublin. 



Royal Irish Academy, January 12. — The Most Rev. 

 and Right Hon. J. H. Bernard, president, in the 

 chair. — ^J. A. McClelland and A. Gilmour : Further 

 observations of the electric charge oni rain. Different 

 sections of the paper deal with the charge on non- 

 thunderstorm rain, thunderstorm rain, snow, and hail. 

 There is also a section dealing with the size of rain- 

 drops. The results agree with earlier observations 

 as regards the great excess of positive charge on non- 

 thunderstorm rain. In the case of thunderstorm rain, 

 while the charge per cubic centimetre is greater, the 

 excess of positive over negative is not inarked. Rain- 

 drops are seldom greater in volume than 5x10-' c.c. ; 

 they are usually less than i x 10-' c.c. Raindrops less 

 than a certain size (008x10-' c.c.) are, as previouslv 

 found, always negatively charged. As a rule, drops 

 of this size give little rainfall, but on a few occasions 

 precipitation of this type was quite considerable. — 

 W. B. Wright : Minor periodicitv in glacial retreat. 

 The terminal moraines of the Killarney and Kenmare 

 district show a marked periodicitv in their arrange- 

 ment, occurring at fairly, regular intervals of half a 

 mile to a mile from one another. These moraines are 

 themselves composite, and break up locallv into 

 smaller moraines. The smaller moraines are pre- 

 sumed to mark annual retreat stages, as in the neigh- 

 bourhood of Stockholm — a presumption which gains 

 support from the occurrence of an e.sker with seasonal 

 mounds between two of the major stages at Kenmare. 

 On this basis the major stages mark a 20- to 40-year 

 periodicity, which is comparable with the cliniatic 

 periodicitv established by Bruckner. A much longer 

 neriodicitv of i;oo or 600 vears, in which an epoch of 

 linear terminal moraine formation alternates with an 

 epoch characterised by the ab.sence of such moraine 

 formation, is vaguely indicated by the evidence, but 

 not proved. 



January 26.— The Most Rev. and Rieht. Hon. T. H. 

 Bernard, president, in the chair. — Prof. .\. Henry 



NO. 2625, VOL. 104] 



and Miss M. G. Flood : The Douglas firs : a botanical 

 and sylvicultural description of the various species of 

 Pseudotsuga. Six species and one variety were 

 investigated. The microscopical structure of the 

 leaves was found to be distinct and constant in each 

 species, being correlated with the special climate in 

 which the tree lives. The Colorado and the Oregon 

 Douglas firs exemplify this well, the leaf-anatomy of 

 the former showing xerophytic features, which are 

 adaptations to the dry continental climate of the 

 Rocky Mountains. These two distinct species {P. 

 glauca and P. Douglasii), usually regarded as of 

 only varietal rank, are treated very fully. The 

 remarkable difference in the odour exhaled by these 

 two trees led to a chemical examination of the oils 

 distilled from their foliage by Mr. C. T. Bennett. 

 The delicious fragrance of the Oregon species was 

 found to be due to the presence in the leaf-oil of 

 geraniol, pinene being absent. The strong turpentine 

 odour of the Colorado species is associated with the 

 presence in its leaf-oil of large percentages of pinene 

 and bornyl acetate. 



Royal Dublin Society, January 27.^Dr. F. Hackett 

 in the chair.— Prof. J. Wilson :" The application of the 

 food-unit method to the fattening of cattle. Thirty 

 years ago N. J. Fjord commenced by experiments to 

 determine what quantities of several other feeding- 

 stuffs were equivalent to i lb. of barley, and his suc- 

 cessors in Denmark and Sweden have so developed his 

 method that there is now scarcely a feeding-stuff the 

 feeding value of which they cannot express in terms 

 of barley, which they have retained as the unit. Manv 

 fattening exj>eriments have been carried out in Britain 

 during the last eighty or ninety years, but, having no 

 very general purpose, they have led to no very definite 

 result. By applying Fjord's method to these experi- 

 ments, however, the relative efficiencies of the various 

 rations can be approximately determined and sugges- 

 tions made for improvement in the use of feeding- 

 stuffs for stock of all kinds. — Prof. H. H. Dixon and 

 H. H. Poole : Phato-synthesis and the electronic 

 theory. The modern view of the part played bv sensi- 

 tisers of the photographic film suggests the hvpothesis 

 that green-leaf pigment, which acts as a sensitiser to 

 the wave-lengths it absorbs, loses electrons under the 

 action of the absorbed light. This would suggest a 

 photo-electric theory for photo-synthesis. .Accordinglv, 

 the photo-electric properties of leaf pigment were 

 tested qualitatively at first by several methods. These 

 giving no indication of photo-electric activity under 

 the action of light active in photo-svnthesis, a more 

 refined quantitative method was employed. This 

 showed that the number of electrons ejected, even 

 under inten.se illumination, from a film of leaf pig- 

 ment or from a layer of leaf-powder is negligible in 

 the photo-synthetic process. The result supports the 

 view that the displacement of electrons, which we 

 should expect to be the first step in photo-svnthesis, 

 must be entirely confined within the pigment-complex 

 of the leaf, or even within the molecules of one of 

 the pigments, and lends no support to the hvpothesis 

 that the pigment, by emitting electrons under the 

 action of light, is able to build up carbohvdfates 

 external to itself. 



Paris. 

 Academy of Sciences, January 19.— M. Henri 

 Deslandres in the chair. — M. Hada'mard : The elemen- 

 tarv solution of linear hvporbolic non-analvtic partial 

 differential equations. — H. Douville : The limit be- 

 tween the Cretaceous and the Eocene in .Vquitaine, 

 India, and the Sudan. — C. Deperet : An attempt at a 

 general chronological co-ordination of Ouaternarv 

 time.— P. Boutroux : A familv of multiform" functions 



