May 9, 191 8] 



NATURE 



199 



this part may divide a little irregularly ; the larger part, 

 however, proceeds normally, as if the first division had 

 been a small prothallial cell. If the first division is 

 equal, each half gives rise to one prothallial cell, tube 

 cell, and body cell. In this case the prothallial cell 

 may be cut off at any side, but only one (and always 

 one) is cut off. The whole process is similar to that in 

 Picea. The mature grain has very distinct walls 

 bounding the prothallial cells, and distinct vestiges of a 

 wall surrounding the generative nucleus. Evidence 

 is also adduced against the idea that the cavities in the 

 stamen apex of the Abietineae are abortive sporangia. 

 In the second part of the paper the development of 

 the female gametophyte is followed but, and, as was 

 to be expected, it agrees accurately with the typical 

 Abietinean plan, including the typical pro-embryo. 

 One marked peculiarity is this : pollen is received by 

 the ovule by a peculiar micropylar development which 

 includes a median constriction and a mass of stigmatic 

 hairs at the opening, exactly as in Pseudotsuga. The 

 pollen in Larix can germinate only on the nucellus, 

 differing in this respect from Pseudotsuga. This is not 

 common, as only one ovule in four has a nucellar 

 grain, and, with few exceptions, one such grain. 

 How the grain reaches the nucellus was not deter- 

 mined. None were so found until June. The main 

 features of the female gametophyte are very similar to 

 Pseudotsuga. In a summary of details it is shown 

 that Pseudotsuga and Larix are very closely allied, 

 though separated in the ordinary classifications. This, 

 however, confirms conckfsions already arrived at by 

 Jeffrey and Penhallow from anatomical data only. 



April 23.— Dr. G. H. Pethybridge in the chair. 

 — R. G. Allen : The insulating properties of erinoid. 

 Results of tests were given for erinoid, an in- 

 sulatoii of comparatively recent origin, and also 

 for vulcanised fibre, which was employed for 

 purposes of comparison and tested under the same 

 conditions as the former material. The tests com- 

 prised the determination of certain physical properties 

 of erinoid, 4ts absorption and retention of water, the 

 electrical resistance of machined and unmachined 

 samples at different temperatures, and the effects of 

 altering the thickness of the samples, changing the 

 value of the applied voltage, and using different elec- 

 trodes. It was found that for both erinoid and fibre 

 a simple relation between resistance and temperature 

 obtained ; that erinoid, but not fibre, was free from 

 dielectric absorption, and machined erinoid was prac- 

 tically independent of the applied voltage. As an in- 

 sulator erinoid was found to be more stable than, and' 

 generally superior to, vulcanised fibre.— Sir John 

 Moore : Solar haloes seen at Greystones, Co. Wicklow, 

 September 22, 1879, and in Texas and Ohio, U.S.A., 

 October 3, 19 17. This was a short communication on 

 a remarkable series of solar haloes which were observed 

 at Houston, Texas, U.S.A., in the forenoon of 

 October 3, 1917. Some hours later a modified form 

 of the same phenomenon appeared at Gallia, Ohio, 

 about 1000 miles (as the crow flies) to the north-east 

 of Houston. An illustrated description of these un- 

 usual haloes was published in the Monthly Weather 

 Review, Washington, October, 1917. Apart from the 

 Intrinsic beauty of the American display, much interest 

 attached to it from the fact that a precisely similar 

 [ihenomenon had been vi-itnessed by the late Sir 

 Ivobert Ball in the forenoon of Septenibcr 22, 1879, at 

 ' .roystones, Co. Wicklow. — Dr. H. H. Dixon : Maho- 

 ^ iny and the recognition of some of the different 



inds by their microscopic characteristics. This paper 



-^ives an account of the microscopic structure of some 



lurty different woods usually marketed as mahogany, 



ind contains a key by means of which these woods 



NO. 2532, VOL. lOl] 



may be recognised by their microscopic characteristics. 

 The structure of the woods described is illustrated by 

 photomicrographs. 



Royal Irish Academy, April 8.— The Most Rev. Dr. 

 Bernard, Archbishop of Dublin, president, in the chair. 

 —J. A. McClelland and P. J, Nolan : The nature of the 

 ions produced by bubbling air through liquids. 

 Previous papers by the authors and by J. J. Nolan 

 have shown the existence of groups of ions of widely 

 different mobilities in air that has been used in the 

 spraying of water or that has been bubbled through 

 water or mercury. The present paper is an extension 

 of this work, and deals mainly with the results of 

 bubbling air through alcohol. The existence of four- 

 teen groups of ions is established, their mobilities 

 ranging from 11 cm. per sec. to 0-00015 cm. per 

 sec. in a field of one volt per cm. The relative 

 amounts of the different ions present depend on the 

 pressure used to force the air through the liquid, and 

 on the time that elapses between the bubbling and 

 the measurement of the mobilities. The nature of 

 these ions is discussed in the paper. 



April 22. — The Most Rev. Dr. Bernard, Archbishop 

 of Dublin, president, in the chair.— H. Ryan, J. Algar,. 

 and P. O'Connell : Syntheses of some new substantive 

 dyes derived from benzidine-sulphone. The prepara- 

 tion of about fourteen dyes from tetrazotised benzidine- 

 sulphone-disulphonic acid by "coupling" with phenols 

 and amines is described ; the influence of the adjunct 

 on the colour is discussed, and the possibility of 

 utilising these substances in medicine indicated. — 

 H. Ryan and T. Glover : The nitro-derivatives of di- 

 phenylamine. The determination of the constitution 

 and the properties of several nitro-derivatives of di- 

 phenylamine was undertaken in order to facilitate the 

 study of the action of the oxy-acids of nitrogen on 

 the base. The authors also describe some new sub- 

 stances which they obtained by the action of nitric 

 and nitrous acids on nitro-diphenylamines. — H. Ryan 

 and Phyllis Ryan : The action of nitric acid and 

 nitrous acid on diphenylamine. Part i. — H. Ryan and 

 J. J. Drumm : The nitro-derivatives of phenyl-2- 

 naphthylamine. 



Paris. 



Academy of Sciences, April 22. — M. P. Painleve in 

 the chair. — ^J. Boussinesq : Partial differential equations 

 for states of sandy masses capable of flow in the 

 neighbourhood of the Rankine-Levy solution. — 

 L. Lecornu : The sign of rotations. In mechanics a 

 rotation is regarded as positive when it is effected 

 from left to right of the observer; astronomers adopt 

 the opposite convention. The author discusses ad- 

 verselv the proposal to reverse the convention in 

 mechanics and to take the same positive sense of 

 rotation as in astronomy. — P. Sabatier and G. Gaudion : 

 The crotonisation of' acetaldehyde, formation of 

 butanol and hexanol starting with ethanol. By the 

 use of copper at 300° C. and uranyl oxide at 360° C. 

 as catalysers, ethyl alcohol can be converted at one 

 operation into crotonic aldehyde, the copper giving^ 

 hydrogen and aldehyde, and the latter being converted 

 into crotonaldehyde' by the oxide of uranium. Better 

 yields are obtained by starting with paraldehyde, 

 the product being crotonaldehyde hexadienal and octa- 

 trienal, separable by fractional distillation. The alde- 

 hydes, by slov^- hydrogenation over nickel at 170° to 

 180° C., can be easily converted into the correspond- 

 ing saturated alcohols, normal butyl alcohol and 

 normal hexyl alcohol.— Ch. Depiret : An attempt at a 

 general chronological co-ordination of Quaternary 

 time. — M. L. Fav^ was elected a member of the 

 section of geography and navigation in succession 



