350 



NATURE 



[July 4, 19 18 



remarkable gynandromorphs of the silkworm and 

 moth which were bred and described by him, for, 

 owing to their important bearing on the problem of 

 sex-determination, they at once received recognition 

 as classical cases. 



An interesting account of the . luminous moss 

 Schistostega osmundacea, Mohr, is given by Mr. G. T. 

 Harris in the Journal of the Quekett Microscopical 

 Club (vol. xiii., April, 1918). The luminosity is due 

 to cer4;ain -cells of the protonema, which, as pointed 

 out by Noll in 1887, are so constructed that the light 

 rays falling upon them are refracted through the 

 transparent sap and concentrated upon the chloro- 

 phyll grains ^vhich are grouped at the base of the cell. 

 Owing to the shape of tho cell, the light rays are 

 totally interriany reflected from the basal walls and 

 again emitted, which gives the luminous appearance. 

 The moss appears to be widely distributed in the 

 British Isles. It seems to prefer a habitat with a 

 northerly aspect, and apparently thrives best in granitic 

 areas. Tfie light-cells are differentiated on the proto- 

 nema, and are spread out in an irregular superficial, 

 layer over the underlying protonemal filaments, which 

 are bipinnately branched. The fruit is somewhat rare, 

 but when it occurs it may be abundant. The distribu- 

 tion of the plant is aided by the deciduous spore- 

 capsules apd by an abundance of gemmae formed on 

 the protonema, especially when barren conditions of 

 the plant prevail. 



Researches carried out by Dr. Lewis H. Weed in 

 the anatomical laboratory of the Johns Hopkins Uni- 

 versity have thrown a flood of light on the origin and 

 nature of the fluid system which surrounds the central 

 nervous system ot vertebrate animals. Dr. Weed was 

 successful in replacing the cerebro-spinal fluid in 

 living pig embryos by a ferrocyanide solution, and 

 was thus able by the deposition of Prussian blue to 

 discover a series of unknown stages in the elaboration 

 of the space in which this fluid is contained. In the 

 first month of development, up to the stage in which 

 the pig embryo has attained a trunk^lerigth of 14 mm., 

 the cerebto.^pinal fluid is confined to the central canal 

 of the nervpus system. At that stage of development, 

 the roof of the fourth ventricle of the brain becomes 

 thin and membranous ; chorioid villi for the secretion 

 of the fluid become developed, and fluid begins to 

 appear in the tissue spaces outside the roof of the 

 fourth ventricle. That accumulation over the roof of 

 the fourth , ventricle represents the first stage in the 

 development of the sub-arachnoid spaces. From the' 

 roof, of the fourth ventricle the sub-arachnoid system' 

 gradually spreads out, and by the time the pig embryo 

 has attained a trunk-length of 26 mm. the system has 

 reached the limits of the extensive ramifications to be 

 seen in the adult animal, in which the spaces sur- 

 round both spinal cord and brain. It is thus clear 

 that the sub-arachnoid spaces are not parts of the 

 lymph system, but are extensions of a special system 

 developed as extensions of the central canal /of . the 

 nerve axis. The aqueous chamber of the eye and . 

 perilymphatic spaces of the inner ear are systems of 

 a similar kind. Dr. Weed was successful in finding 

 further and convincing evidence of the secretion of 

 cerebro-spinal fluid by the chorioid plexuses and of its 

 absorption into the great venous sinuses of the dura 

 mater by a . special mechanism, represented in the 

 adult by the Pacchionian villi. Mucli still remains 

 to be done before the exact uses of the cerebro-spinal 

 fluid are determined. Dr. Weed's researches have 

 been published ih full by the Carnegie Institution of 

 Washington (Contributions to Embryology, vol. v., 

 No. 14, 1.917). 



NO. 2540, VOL. lOl] 



In Bulletin No. 28, entitled "The Soil Solution 

 Obtained by the Oil-pressure Method," issued by the 

 Michigan Agricultural Experiment Station, it is 

 pointed out that the study of the liquid phase of the 

 soil might yield much valuable information as regards 

 soil fertility if a satisfactory method of obtaining a 

 representative sample could be devised. An oil-pres- 

 sure method is recommended, in which paraffin oil is 

 forced through the soil enclosed in cylinders, thus dis- 

 placing the soil solution. The physical and chemical 

 properties of successive poi-tions extracted from a ; 

 given soil were found to vary very little, the greatest -, 

 variation occurring in the nitrogen compounds, 

 especially in thfe ammoniacal and nitrate nitrogen ; the; 

 total nitrogen, however, did not change. From 

 different soils the extracts differed ; soil treatment and 

 reaction cause considerable variation in potassium, 

 calcium, magnesium, and especially nitrogen ; phos- 

 phoric acid varies only slightly. 



At the present time the use of electric furnaces is' 

 spreading rapidly in this country. In view of their 

 further possibilities, the need for researches on the ; 

 production and application of high temperatures is, 

 urged by Mr. C. R. Darling in an article contributed: 

 to the Journal of the Society of Chemical Industry for 

 May 31. To emphasise the point as regards electric' 

 furnace research, the writer notes what has already, 

 been achieved by its use in transforming certain. 

 Common materials. Coke and lime give calcium car- 

 tide, which in turn yields acetylene and cyanamide.; 

 Coke and sand give carborundum, an abrasive now 

 used throughout the world ; and the fusion of 

 bauxite gives another abrasive, alundum, which has 

 practically superseded other materials for the grinding 

 of steel. Amorphous carbon yields graphite, which 

 is now invaluable in electrolytic processes, and has 

 proved to be the best material for filling dry voltaic 

 cells. These products have revolutionised many indus- 

 tries, but they represent only the beginning. Inves-! 

 ligations are needed, for example, on the conditions- 

 under which tungsten could be melted .on a reason- 

 ably large scale, and valuable results might be ex- 

 pected from a study of the possible alloys obtainable; 

 from tungsten, tantalum., and molybdenum. Research' 

 work of the character required is being carried out in 

 America, but practically nothing has been done in this 

 country, though ; a start is being made at Sheffield-. 

 University by the erection of an, electric furnace for; 

 experiments on steel. The practicabilitv. of producing, 

 high temperatures by the combustion of gases under- 

 pressure is also a matter for investigation ; Sir Robert- 

 Hadfield has recently directed attention to some early' 

 experiments of Bessemer in this direction. >. 



In the Metropolitan Museum of Art, New York,! 

 is the tomb of Perneb, originally erected at Memphis' 

 about 2650 B.C. Mr. M. Toch has had an opportunity' 

 of analysing the pigments used on the tomb, and 

 gives an interesting account of them in a paper quoted 

 by the Chemical News of June 7. The pigments are' 

 red, yellow, blue, green, grey, and black. The u.'ual 

 idea "that the red used by the Egyptians was red; 

 ochre appears to be erroneous ; the red found in thi.s; 

 instance proved to be haematite, which contains much; 

 more iron oxide than the ochres. All the yellows used; 

 on the tomb were composed of the native ochre, which' 

 is clav coloured with iron-rust. The Egyptian blues 

 are beautiful colours, ranging from a light sky-blue 

 to a dark ultramarine. A microscopical examination 

 of the dark blue showed it to be of the nature of a 

 powdered "smalt" glass or porcelain ; this powder has 

 been rubbed into the pigmented surface and allowed to 

 set with Nile clay or mud, which, being .slightly alka.- 



