November 17, 1923] 



NA TURE 



745 



H^r 



B^^ 



Societies and Academies. 



London. 



Royal Society, November 8. — A. S. Parkes : Studies 

 on the sex-ratio and related phenomena — fcetal 

 retrogression in mice. By means of corpora lutea 

 counts it was found that in mice the average amount 

 of fcetal mortality leading to retrogression was 

 IO-8 per loo normal foetuses. Daniel and King 

 have shown for mice and rats respectively that the 

 does ma}^ become pregnant at the oestrus period 

 which follows within twenty-four hours after parturi- 

 tion, and that the gestation period of the second 

 litter is prolonged in some cases as much as ten days. 

 This abnormal prolongation of the embryonic stages, 

 which is due to inhibited implantation in the uterine 

 mucosa, can be used experimentally to determine 

 the effect of unusually adverse conditions upon 

 embrj'onic and foetal mortality. Where the previous 

 young were suckled less than six days, the amount 

 of mortality ro.se to 17-6 per 100 normal foetuses, 

 while in prolonged gestations resulting from con- 

 tinued suckling of previous young, the amount of 

 mortality was further increased to 23-1. The sex- 

 ratio of young bom in these two classes was respect- 

 ively 80-4 and 62-1 males per 100 females. Since 

 the normal sex-ratio of mice is not far from equality, 

 this inverse correlation between the amount of foetal 

 mortality and the sex-ratio of the surviving foetuses 

 suggests that mortality during gestation falls pre- 

 ponderatingly upon the males. — R. A. Fisher : The 

 mfiucnce of rainfall on the yield of wheat. The 

 Rotliamsted data for rainfall and wheat yields extend 

 to 1854 ; these data have been utilised to calculate 

 the average effect on the yield of rain at different 

 riods of the harvest year, for plots under 13 different 

 nurial treatments. An extension of the method 

 f partial correlation, applicable when the number 

 t independent variates is very large and can be 

 nranged in a continuous series, is used. The several 

 l)lots show marked differences in their response to 

 rain, showing that it is not impossible for the farmer 

 to adapt his manurial treatment to a wet or dry 

 season. A large part of the differences may be 

 .1 scribed to the effects of loss of soil nitrates by per- 

 colation ; other effects not susceptible to this explana- 

 tion, and not hitherto anticipated, include the losses 

 on the highly nitrogenous plots due to late summer 

 rain. The residual value of artificial nitrogenous 

 manures appears from these results to be considerably 

 reater than has been thought. — D. Thursby-Pelham : 

 '> he placentation of Hyrax Capensis. The early 

 development of Hyrax is unknown, but there is no 

 embedding of the blastocyst which undergoes its 

 development in the uterine lumen. The maternal 

 epithelium is destroyed early by the trophoblast on 

 all sides. The trophoblast is differentiated into two 

 cytotroplioblastic layers : — (i) basal phagocytic layer 

 ^basal trophoblast) ; (2) cellular network enclosing 

 lacunse of maternal blood (inner trophoblast). The 

 placentation throws little light on the affinities of 

 Hyrax. While it agrees with the placenta of rodents 

 in being haemochonal, it differs in its zonary form 

 and the detailed character of its trophoblast. Super- 

 ficially it bears some resemblance to the placenta 

 of Elephas in zonary arrangement and great com- 

 plexity of allantoic villi, but in Hyrax there is no 

 syncytial layer of maternal tissue surrounding the 

 villi as in Elephas. Our present knowledge of the 

 placentation of Hyrax tends to emphasise the 

 isolated position the order occupies among Eutheria. 



Physical Society, October 26. — Dr. Alexander 

 nsscll in the chair. — S. H. Piper and E. N. Grindley : 



NO. 2820, VOL. 112] 



The fine structure of some sodium salts of the fatty 

 acids in soap curds. X-ray photographs of certain 

 sodium salts of the fatty acids (soap curds) show 

 lines due to reflections from planes with very wide 

 spacings of the order 40 A.U. These planar spacings 

 increase uniformly with the number of CHj groups 

 in the molecule, indicating an effective length of 

 1-25 A.U. for the CHj group. These and other 

 lines can be accounted for by assuming that the curds 

 are in the smectic state described by Friedel. — E. A. 

 Owen and G. D. Preston : X-ray analysis of solid 

 solutions. The atomic structure of solid solutions 

 of copper-aluminium, aluminium-magnesium, and 

 copper-nickel has been examined by the X-ray 

 spectrometer. In each case it was found that the 

 solute atom replaces an atom in the lattice of the 

 solvent, the substitution being accompanied by a 

 distortion of the lattice. The eutectic alloy of 

 aluminium and copper consists of a mixture of two 

 distinct substances with different space lattices, one 

 being CuAlg and the other a substance the space 

 lattice of which cannot be distinguished from that 

 of pure aluminium. The intermetallic compound 

 CuAlj possesses a simple tetragonal lattice of side 

 4-28 A.U. and axial ratio 0-562, the copper atoms 

 being at the corners and the aluminium atoms at the 

 centres of the four small faces. The atomic structure 

 of the compound CuAl resembles that of a soUd 

 solution of aluminium in copper, but the distortion 

 is considerably greater. The material has a face 

 centred trigonal lattice of side 3-89 A.U. and an 

 angle between the axes of 94-6°, the iii planes 

 being composed alternately of aluminium and copper 

 atoms. — H. Chatley : Cohesion. The consequences 

 are discussed of assuming that the alternately positive 

 and negative atoms in a crystal may be treated as 

 doublets attracting according to an inverse fourth- 

 power law, while the electron fields surrounding the 

 atomic nuclei repel according to an inverse tenth- 

 power law. The numerical results agree fairly well 

 with the facts as regards the strain which produces 

 rupture in solids, and as regards tlie rate of change 

 of compressibility with compression in liquids. 



Linnean Society, November i. — Dr. A. B. Rendle, 

 president, in the chair. — S. Garside : The forms of 

 Hypoxis stellata, Linn, f., a South African species 

 of Amaryllidaceae. Four varieties are distinguished, 

 one of these as yet undescribed. In each case the 

 varieties have constant vegetative characters, but 

 the flowers show a considerable range of colour 

 variation of a " continuous " kind. Important 

 cytological characters of the upper epidermis of the 

 perianth lobes were described, with particular refer- 

 ence to the remarkable iridescent areas which occur 

 in some varieties. Habitat may considerably in- 

 fluence the size of the plant, but the varietal char- 

 acters remain constant. — H. A. Baylis : The host- 

 distribution of parasitic thread-worms (nematodes). 

 The nematodes parasitic in vertebrates show great 

 variety in the extent to which they are limited to 

 particular hosts. They may be divided broadly 

 into a section with more or less strict " specificity 

 and a section with members occurring in various 

 hosts, often of quite distantly related groups. Many 

 of the latter have an intermediate host (commonly 

 an invertebrate) during their earlier phases, and these 

 forms, being introduced into the final host at a 

 more advanced stage than those which have a direct 

 development, may be better able to adapt them- 

 selves to a variety of final hosts. Among forms with 

 a direct development, those which show the strictest 

 specificity arc probably the most specialised, this 

 being often correlated with specialisation, in habits 



