November 30, 191 ij 



NATURE 



i<>5 



Mineralogical Society, November 14. — Anniversary meet- 



.g. — Prof. W. J. Lewis, F.R.S., president, in the chair. 



— R. ii. Solly : Dufrenoysite, associated with seHg- 



mannite, from the Binnental. In a small cavity, dis- 



vered in August, in the dolomite rock in the Lengenbach 



jarry, were a few brilliant crystals of dufrenoysite, coated 



. their fractured surfaces with minute crystals of selig- 



mannite. Measurements of two crystals of the former led 



to the discovery of twenty-six new forms. — H. G. Smith : 



A simple graphic method for determining extinction-angles 



in sections of biaxial crystals. A means of drawing a 



ystal projected on any plane and finding the extinction- 



ections was explained. — Dr. G. T. Prior : The meteoric 



■ne which recently fell in Egypt. A meteorite fell on 



ne 29 near the village of Abdel Malek, about 44 km. 



S.E. of Alexandria. It exhibits a brilliant, varnish-Hke 



1st, and consists mainly of a coarse-grained crystalline 



i^regate, without chondrules, of a green pyroxene and a 



)wn ferriferous olivine with only a little felspar and 



ictically no nickeliferous iron. A quantitative analysis 



)wed that the stone includes a high percentage of lime, 



i that the green pyroxene, containing much lime as 



11 as ferrous oxide and magnesia, constitutes about 



three-quarters of the stone by weight. A study of thin 



s'-ctions under the microscope showed that the pyroxene is 



nerally twinned on 100, gives extinction angles as high 



35°, and exhibits " herring-bone " structure owing to 



i.M-i twinning on 001. — T. Crook and S. J. Johnstone : 



Striiverite from the Federated Malay States. A mineral 



of doubtful identity found in the course of tin-mining on 



Sebantum River, Kuala Kangsar district, Perak, was 



'ved to be striiverite ; it closely resembles the mineral 



■3ntly recorded by Hess and Wells from South Dakota, 



"'.A. — A. Hutchinson : The temperature at which 



!)sum becomes optically uniaxial. A small plate of 



isum, cut normal to the acute bisectrix, was placed in 



^lass-topped cell, through which a stream of water at a 



rminate temperature was passed, and the optic picture 



I- studied under a microscope. The plate became 



uniaxial at 25° C. — A. Hutchinson : A total-reflection 



diagram. From this diagram the refractive index of a 



suij'^tance is graphically determined when given the angle 



of total reflection with respect to a known substance of 



' u^her refractive index. By taking the sine of the angle 



coordinate, the curves are straight lines. — T. Crook : 



occurrence of ankerite in coal. The white crystalline 



rs often found as infillings of the vertical joints in 



■fish coal are ankerite. Dolomite was not found, and 



' ite occurs sparingly as compared with ankerite in the 



' imens examined. 



Royal Microscop'cal Socirty, November 15.— J. E. 



Barnard : A gr-ometric slide photomicrographic apparatus. 



apparatus was designed on the principle of the geo- 



ric slide throughout, as enunciated by Lord Kelvin and 



•. The base of the apparatus was formed of two cast- 



- designed on the girder principle, braced together at 



!i end and in the middle. The portion to carry the 



loscope was also formed by a pair of castings braced 



ther in the same way. Great rigidity was obtained, 



1 the whole apparatus would move together if subjected 



-liock or vibration. Rods were fastened down on the 



of the castings to support the apparatus, and the 



I'-ra slid along these on two V-grooves on one side and 



a plane surface on the other side. The camera was 



M)orted on vertical rods fixed on the geometric slides. 



apparatus could be used equally well as a horizontal 



or v.-rtical camera, or at an angle of 45°. — Rev. Hilderic 



Friend : Fridericia. The genus Fridericia was created by 



liaelsen in 1889 to receive certain species of Enchytraeids, 



■n in number, possessed of dorsal pores and having 



1 of unequal lengths. In 1895 Beddard reckoned twelve 



ies, but not one was known as British. Moore, Friend, 



I others added to the list, which in 1900 stood at twenty- 



Bretscher, Issel, and others then took up the study, 



! at the present time some seventy or eighty species of 



1 "ricia are known to science. The largest is F. magna, 



lid, which has been found in England, Ireland, and 



iland, but so far has not been reported abroad. The 



lor, whose researches into this genus began in 1896, 



records no fewer than thirty species found up to the 



present time m the British Isles. Some of these are new 

 to science ; and a series of keys is appended to enable the 

 student readily to distinguish the allied species. 



Linnean Society, November 16.— Dr. D. H. Scott, F. K.S., 

 president, in the chair.— Dr. R. R. Gates : Certain aspects 

 ot^ the mutation problem in CEnothera. Work with the 

 CEnotheras has developed in several directions, all bearing 

 on the general question of the place to be assigned to muta- 

 tion as an evolutionary factor. A concerted attack upon 

 ; the behaviour of the Oinotheras in heredity and variation 

 I from several points of view gives a broader basis for the 

 I interpretation of the evolutionary significance of these 

 j phenomena than has hitherto been possible in most other 

 genera. The cytological evidence has shown that in most 

 of the mutants from CEnothera Lamarckiana the chromo- 

 some number is unchanged, but in the mutant CE. gigas it 

 is doubled. Hence mutants originate in various ways. 

 Evidence goes to show that the chromosome doubling in 

 fE. gigas probably occurred either in the fertilised egg or 

 in a megaspore mother-cell, which afterwards developed 

 apogamously. On the other hand, in certain cases the 

 niutational change probably occurred during the reduction 

 divisions. Thus CE. rubricalyx is a mutant from CE. rubri- 

 nervis, which produces an extreme amount of pigment ; 

 and when crossed with the parent type the new character 

 behaves as a Mendelian dominant, and in such a way as 

 to show that the original mutant individual was hetero- 

 zygous, and probably originated from a cross between a 

 germ-cell in which the new dominant character appeared 

 and one in which it was lacking. From this and much 

 other evidence mutation in Qinothera appears to be due 

 to a general condition of germinal instability, which in 

 turn is probably connected with crossing in the ancestry. 

 This, however, by no means deprives it of evolutionary 

 significance, for all open-pollinated species of plants are 

 hybrids in the sense that various races have participated 

 in their immediate ancestry. Certain results were also 

 communicated of CE. grandifloraxCE. rubricalyx, CE. 

 Lamarckiana X CE. grandiflora, and other crosses which 

 produce twin types. — G. Claridge Druce : Some floristic 

 results of the International Phytogeographic Excursion 

 through the British Isles. — A. W. Hill : Drawings of a 

 viviparous specimen of Juneus bufonius. The seedlings 

 were seen emerging from the parent capsule. — N. C. 

 Macnamara : Mutations in foxglove plants. From a 

 packet of foxglove seeds (Digitalis purpurea) sown in the 

 year 1906, fifty-four plants were, in June, 1907, planted in 

 a shrubbery of fir trees with an undergrowth of laurels. 

 Of these plants fifty-one grew into normal foxgloves, but 

 the three remaining plants were sports, which we may dis- 

 tinguish by the letters A, B, and C. A. In this plant the 

 flowers of the lower half of the stem possessed only a 

 bifid upper petal and seven stamens united at their bases. 

 The flowers of the upper part of the spike were normal. 

 B. A fine, well-grown plant 4^ feet high ; throughout the 

 whole length of the spike the flower consisted of a bifid 

 upper petal, seven stamens, and style. The upper part of 

 this spike was isolated ; it produced abundant self-fertilised 

 seed. C. The spike of this plant grew to be 5 feet high ; 

 from base to apex its flowers consisted of nine stamens and 

 a style, with no vestige of petals. It seems that a certain 

 number of the foxglove seeds sown in the year igoli con- 

 tained elements in a condition such as that described by 

 de Vries as being " impressed by an impulsive mutability," 

 for some of the flowers produced by these seeds were 

 sports. Seeds from these sports produced their like in 

 1909 ; and, further, these latter plants produced some 

 terminal flowers totally differing in character from the 

 parent sport from which they were derived. Seeds from 

 these terminal flowers produced their like in the year 1911 ; 

 so that there are now two different strains of foxtjldv.- 

 plants produced from the seeds sown in 1906, and tli--. 

 strains have been produced from self-fertilised flowers, thai 

 is, from flowers carefully protected from insects or other 

 means of cross-fertilisation. 



Dublin. 



Royal Irish Academy, November 13.— Rev. Dr. Mahaffy, 



president, in the chair.— R. Llovd Praever : Phaner- 



gamia. Part ii. (Clare Island Survey.) On a former 



occasion the question of the origin of the island flora, 



NO. 2196, VOL. 88] 



