March, 1911. 



KNOWLEDGE. 



107 



Monocotyledons (e.g. grass seedlings), the stimulus can be 

 transmitted from the receptive surface of the leaf to the lower 

 parts of the plant. 



MALE NUCLEI IX FLOWERING PLANTS.— Some 

 years ago, Nawaschin observed that when the pollen-tube of 

 an Angiosperm — he worked with Liliiiin niurtagaii and 

 Frifillaria tcncUa — reaches the embryo-sac, both of the 

 male or generative nuclei enter the sac, one fusing with the 

 egg and the other with the central nucleus (variously called 

 the "'secondary" or "definitive" or "fused polar" nucleus), 

 the embryo arising as the result of the former fusion, 

 and the endosperm as the result of the latter. This 

 remarkable discovery, which was made almost simultaneously 

 by Guignard. and has since then been confirmed in a 

 large number of Monocotyledons and Dicotyledons from 

 the lowest to the highest families, also led to the observation 

 that the male nuclei are elongated and worm-like, or even 

 spirally coiled, like the body of the motile male cells of lower 

 plants, and Nawaschin suggested that these nuclei might have 

 the power of independent locomotion. Most later writers have 

 rejected this view and considered that these nuclei are carried 

 along passively by streaming of the protoplasm in the embryo- 

 sac, but Nawaschin has recently (Oesterr. hot. Zcifsclir., 

 1909; Ann. jard. hot. Buitcnzorg. 1910) obtained evidence, 

 almost amounting to positive proof, that the two sperms 

 actually move towards the two nuclei with which they fuse, 

 and that when spirally coiled like a cork-screw they rotate 

 during their passage through the embryo-sac, and thus burrow 

 through the protoplasm on their way to the egg and the polar 

 nuclei. 



CHEMISTRY. 



By C. .AiNSWORTH Mitchell. B..A. (O.xon.), F".I.C. 



TEIRODON POISON.— Various species of Tctrodomn' 

 are common in the seas of Japan, and are extensively used as 

 food, after removal of the ovaries, in which is secreted the 

 characteristic poison of the fish. This toxic substance, which 

 is not present in the flesh, has been investigated by Mr. X. 

 Tahara iBioclieni. Zcits., 1910, xxx, 2551, who isolated it by 

 grinding up the ovaries of the fish with water, concentrating 

 the liquid, and precipitating albuminous substances and 

 phosphates. On now adding ammonia to the filtrate the 

 poison was precipitated in an impure condition, and was 

 subsequentlypurifiedby repeated treatment with lead acetate and 

 ammonia, and extraction with alcohol, in which it was partially 

 soluble. As thus purified tetrodon poison was a white powder, 

 which absorbed moisture on exposure to the air. It was nearly 

 insoluble in most organic solvents, and was only sparingly 

 soluble in water. Its reaction was neutral, and it is therefore 

 suggested that it should be termed tctrodoto.xine. instead of 

 tetrodonic acid, as heretofore. Apparently it was neither an 

 alkaloid nor a protein, but formed precipitates with the 

 hydroxides of heavy metals, and on treatment with dilute 

 hydrochloric acid was decomposed, with the formation of a 

 basic substance and a crystalline body containing no nitrogen. 

 The preliminary analyses indicated that tetrodotoxine had a 

 composition agreeing with the formula Ci.;HxiNOi,:. and this is 

 provisionally assigned to it. Physiological experiments proved 

 that the toxine was very active. 



FILAMENTS FOR ELECTRIC LAMPS.— The modern 

 methods of preparing the filaments for incandescent electric 

 lamps are particularly ingenious, and illustrate the ways in 

 which chemical processes may be used to overcome apparently 

 insuperable difficulties. The carbon filaments are now almost 

 universally made by a method similar to that used in the 

 manufacture of artificial silk. A solution of nitrocellulose 

 (collodion cotton) in acetic acid is rapidly pressed through a 

 small opening, and the resulting filaments are twisted into the 

 required shape round carbon blocks, which are placed in 

 bo.xes of fire-proof clay and heated in a furnace until the 

 filaments are carbonized. They are then heated, by means of 

 an electric current, in an atmosphere of benzine, so as to 

 remove the last traces of volatile substances. It is essential 

 that the carbonised filament should be homogeneous through- 



out, and that, as far as possible, it sho-ild have been converted 

 into the graphic form of carbon, which is not decomposed so 

 rapidly by the current, and thus reUrds blackening of the 

 glass. 



The amount of electricity consumed i/ .■ carbon lamps has 

 led to the extensive use of lamps containing ;r;etallic filaments, 

 and an interesting survey of the diffeient processes that are 

 being used for the production of these is given by Mr. H. 

 Baumhauer in the Zeit. angcw. Cliem. (1910. xxiii., 2065). 

 The only metal of sufficiently high melting-point that has been 

 found suitable for the direct production of filaments from the 

 pure metal is tantalimi. and tantalum lamps have now been 

 sold for some years. 



It was shown by Weiss [Zcit. aiiorg. Cheni., 1909, Ixv., 

 288) that titanium and zirconium melted at too low temperatures 

 to be available for the purpose, while he was unable to melt 

 tungsten, the estimated melting-point of which is 2800°C. 

 Owing to this, it has not been found possible to prepare 

 filaments of tungsten directly from the metal, but the problem 

 has been solved in other ways. Thus, in one type of lamp no 

 longer on the market, tungsten filaments were prepared by 

 coating carbon filaments with a deposit of sublimed tungsten 

 chloride, and then heating them in a current of hydrogen to 

 reduce the tungsten compound to the metallic form, and expel 

 the carbon. Owing to the low resistance offered by the 

 filaments this process was abandoned, and at the present time 

 tungsten filaments are made by mixing tungsten oxide with an 

 excess of zinc dust and heating the mixture in a loosely- 

 covered iron vessel until the reaction takes place. The zinc is 

 then dissolved from the mass by means of hydrochloric acid, 

 and the reduced metallic tungsten is left in the form of a black 

 powder. This is made into a paste with caramel or gum 

 tragacanth, and is forced through minute openings, so as to 

 form filaments, which may be dried and heated in a current of 

 hydrogen to expel the carbonaceous agglutinating material. 



.•\ still more recent method of manufacturing tungsten 

 filaments is by means of a colloidal solution of tungsten 

 obtained by alternately treating the metal with acid and 

 alkaline reagents, so as to obtain a flocculent gelatinous mass. 

 This is separated from water by squeezing it in silk, and is 

 then ready to be made into filaments without the necessity 

 of adding any binding substance. This process is used in the 

 manufacture of the "Sirius" and "Colloid" lamps, while in 

 the case of other tungsten lamps a binding material is also 

 employed. 



Attempts to use other metals of high melting-point, such as 

 osmium and zirconium, have not proved nearly so successful 

 as the methods in which tungsten is used alone, and processes 

 of adding metals to the carbon filaments in the ordinary lamps 

 have also proved unsatisfactory. Thus, according to Mr. 

 Baumhauer, a lamp recently put upon the market contained 

 carbon filaments coated with zirconium, but although at first 

 there was greater emission of light and smaller consumption of 

 electricity, the life of the filament was considerably shortened, 

 and the consumption of electricity soon rose to that of an 

 ordinary carbon lamp. 



GEOLOGY. 



Bv Russell F. Gwinnell, B.Sc. A.R.C.S.. F.G.S. 



THE ORIGIN AND PEOPLING OF THE DEEP SEA. 



— Under this title a translation of a paper by Professor 

 Johannes Walther appears in the American Journal of 

 Science for January. Comparing land and water. Dr. 

 Walther points out that while temperature decreases with 

 height and depth respectively, in the ocean great depths, 

 and hence low temperatures, preponderate. Half the Earth's 

 surface is deep sea, with an average depth of four thousand 

 metres and a maximum of from eight to ten kilometres. The 

 inhabitants of this great area are considered with especial 

 reference to the light which they throw on the origin of the deep 

 sea. The characteristics of abyssal depths are: — (1) a uniformly 

 low temperature; (2) quiet water, with no noticeable movement; 

 (3) no light, and as a consequence no green-plant life. Hence 

 all light-hungry and plant-eating animals, and all which need 

 moving and warm water, are absent ; nevertheless, life is 



