December 24, iqhJ 



NATURE 



459 



results. For instance, it is generally recognised that 

 protoplasm is a colloidal complex, apparently existing 

 both in the hydrosol and hydrogel state, the two 

 states being' spontaneously reversible ; the process of 

 germination of fungus spores, followed by the dark- 

 ground method, showed the gradual conversion of 

 the gel contents of the spore into a hydrosol on 

 absorption of water, and later a formation of a gel 

 might occur again. The nucleus and chloroplasts are 

 probably specialised parts of the plasma with a 

 hydrogel structure, but only in favourable cases could 

 the nucleus be studied. Particles and vesicular bodies 

 (which the author terms "sap particles") were usually 

 found in the cell-sap and showed a continuous 

 Brownian movement; they usually increased in 

 number with decreasing vitality of the cell. 



The problem of the dolomitisation of limestone has 

 received an interesting contribution from Prof. R. C. 

 Wallace, of the University of Manitoba (Compte-rendti 

 of the twelfth International Geological Congress, 19 14, 

 p. 875). He regards the concentration of magnesium 

 ions in the solution from which dolomite is precipi- 

 tated as in many cases the determining factor. This 

 concentration at moderate depths of sea-water may 

 determine whether calcite or dolomite is stable; at a 

 certain concentration of magnesium, calcite goes into 

 solution and dolomite is deposited. In a solution in 

 which calcite is stable, magnesium carbonate may be 

 unstable, and may go into solution until the mag- 

 nesium ions are sufficiently abundant to produce a 

 precipitation of dolomite. In the case, again, of 

 underground water bringing magnesium into a lime- 

 stone, a solution may abruptly arise in which calcite 

 is unstable and becomes replaced by dolomite. It will 

 be seen that this view differs from the older one of 

 the mere substitution of magnesium for part of the 

 calcium present in a mass of calcium carbonate. 



We have received from Prof. Eredia a pamphlet 

 entitled "The Organisation of the Service of Weather 

 Predictions in Italy," reprinted from the Rivista 

 Meteorico-Agraria (vol. xxxv., 50 pp.). An experi- 

 mental system of weather telegrams was instituted in 

 the Papal States from July to December, 1855, and 

 the observations were forwarded to Padre Secchi for 

 e;xamination. His report of the experiment was 

 favourable, but practically the commencement of the 

 service dates from April, 1866, when observations were 

 telegraphed to the central office at Florence. After 

 the removal of the latter to Rome the service was 

 frequently improved, under the direction of Prof. 

 Tacchini, and the daily weather report has latterly 

 again been considerably enlarged. The present direc- 

 tor is Prof. L. Palazzo, whose name is well known to 

 many of our readers by the interest he takes in geo- 

 physics generally. Prof. Eredia also gives a brief 

 sketch of the origin of the weather service in Europe. 

 With reference to this country- he remarks that in 

 i860 the Astronomer Royal informed M. Le Verrier 

 (Paris) of the proposed establishment of a service on 

 our coasts, and requested an exchange of bulletins. 

 This is strictly true, but it might be explained that the 

 communication was in reply to an inquiry by M. Le 

 NO. 2356, VOL. 94] 



Verrier, which would naturally have been referred to 

 .Vdmiral FitzRoy before being dealt with. The latter 

 issued daily weather reports to newspapers from Sep- 

 tember 3, i860, and storm warnings from t'ebruarj- 5, 

 1861. It may be worth while to direct attention to 

 two apparent slips in the last paragraph but one on 

 p. 7 of Prof. Eredia 's laborious and useful compilation 

 (with reference to a storm on December 1-2, 1863) : 

 Lvlanda should read Irlanda, and M. Davy is quoted 

 as director of the English service. 



Ix a review of Dr. Hobson's 'Squaring the Circle " 

 in the Bulletin of the .American Mathematical Society 

 for November, ProL R. C. Archibald directs attention 

 to the early use of the symbol - by \\illiam Oughtred 

 (1574-1660) in his "Clavis Mathematica " of 1631 and 

 in his 'Theorematum in Libris Archimedes de 

 Spheara et Cylindro Declaratio " (Oxford, 1652). 

 Oughtred employs the symbols 8 : n- to represent the 

 ratio of the semidiameter to the semiperiphery of the 

 circle, although he does not use the symbol n- separ- 

 ately. He states specifically that -R/6 is the semi- 

 periphery of a circle of radius R. Prof. Archibald 

 further directs attention to references to squaring the 

 circle in the Birds of .Aristophanes (produced 414 

 B.C.), lines 1004-5, and in the last canto of Dante's 

 •Paradiso" (canto t,:^, lines 133-5, i" Cary's transla- 

 tion), and he points out that Longfellow, in his trans- 

 lation, gives "to square the circle" as the equivalent 

 of the Italian " Misurar lo cerchio." 



Ix an article on "The Conic as a Space Element," 

 in the Transactions of the American Mathematical 

 Society, xv., 4, Mr. Roger A. Johnson develops a 

 system of co-ordinates for the conic in three dimen- 

 sion space analogues to the line co-ordinates of 

 Pliicker, by treating the conic as a degenerate 

 envelope. It is interesting to note that the problem 

 of the conic in space has been studied for the last 

 sixty years, and that in 1908 the Belgian Royal 

 Academy announced the offer of a prize for a dis- 

 cussion of the subject. It may, however, be pointed 

 out that the problem of the aeroplane in space is at 

 the present time of a far more urgent character, and 

 that the most pressing need is for pure mathematicians 

 who find no difficulty in dealing with cumbersome 

 formulas as abstract as those which occur in connec- 

 tion with these harmless but unprofitable conies. 

 Still, it is interesting to learn that the totality of 

 conies of a T, that touch two fixed planes, the inter- 

 section of which does not meet the axis of the T„ 

 constitute a T, of the most general type. 



OUR ASTRONOMICAL COLUMN. 

 The Approachixg M.aximum of o Ceti.— Accordini- 

 to prediction, o Ceti or .Mira will be at its maximum 

 brightness on February 11 next, but it should be noted 

 that both the star's period and brightness are not 

 alwavs the same at each return to its full brilliancy 

 \s the star remains at its maximum brightness 

 {20 mag.) for about fourteen davs, it will be at a 

 maximum on February 4 (appro.x.). At the present 

 time It is a conspicuous ruddv object in a 4-in tele 

 scope (mag about 6^0), and its spectrum discloses the 

 I strikingly brilliant flutings and the bright hvdrogen 



