NA TURE 



[May 5, 1892 



Messrs. W. and A, K. Johnston have issued, under the 

 authority of the Royal Agricultural Society of England, a 

 valuable series of eight diagrams representing the life-history of 

 the wheat plant. The diagrams are reproductions of original 

 drawings by Francis Bauer, now in the Botanical Department 

 of the British Museum, and are printed in colours. With each 

 set is sent a pamphlet by William Carruthers, F.R.S., con- 

 sulting botanist to the Society, entitled " The Wheat Plant : 

 How it Feeds and Grows." This pamphlet consists of notes 

 explanatory of the diagrams. 



Dr. L. Meschinelli and Dr. S. Squinabol announce for 

 publication a Tertiary Flora of Italy. 



Four lectures upon recent stellar spectroscopy and the 

 new star in Auriga will be delivered in Gresham College, by 

 the Rev, Edmund Ledger, at 6 p.m. on the evenings of May lo, 

 II, 12, and 13. 



Another contribution lo our knowledge of the sugars and 

 their related compounds is published by Prof. Emil Fischer in 

 the current number of the Berkhte. It relates to the constitution 

 of the group of substances at the head of which stands dulcitol, 

 CHgOH— (CH0H)4— CH.2OH, the hexahydric alcohol ob- 

 tained from Madagascar manna, and prepared artificially by the 

 reduction of milk sugar. It has already been established that 

 the aldehyde corresponding to dulcitol is galactose, CHgOH — 

 (CH0H)4 — COH, the glucose obtained from many gums, and 

 which is formed when milk sugar is boiled with dilute acids. 

 Moreover, it has long been known that, when either dulcitol or 

 galactose are oxidize! by means of nitric acid, a dibasic acid of 

 the composition COOH— (CH0H)4-(C00H) is produced. 

 This acid, although expressed by the same formula as saccharic 

 acid, the acid obtained by the oxidation of common cane-sugar, 

 differs considerably in properties from that acid, and has been 

 termed mucic acid. It is now known to be a geometrical isomer 

 of saccharic acid— that is to say, the two compounds only differ 

 with regard to the relative positions of the atoms comprising 

 their molecules. Saccharic acid, as obtained from cane-sugar, 

 is probably unsymmetrically built up, for its solution rotaies the 

 plane of polarization of light to the left. The main result of the 

 work now described has been to show that the molecules of 

 mucic acid are, on the contrary, symmetrically constructed, and 

 that its observed optical inactivity is due to this fact. Theoretical 

 considerations, based upon the postulates of the Van 't Hoff- 

 Wislicenus hypothesis concerning the arrangement of carbon, 

 hydrogen, and oxygen atoms in space, lead to the view that, of the 

 ten possible geometrically-isomeric dibasic acids of the constitu- 

 tion (CH0H)4 . (C00H)2, two must be optically inactive. 

 These two optically inactive isomers would be represented re- 

 spectively by the formulae 



II H H H 



I I I I 

 COOH— C—C—C—C— COOH 



I I I I 



and 



OHOHOHOH 



H OH OH H 



I I I I 

 COOH— C—C—C—C— COOH. 



I I I I 

 OH H H OH 



One of these two was presumably mucic acid. It was evident 

 that if the molecules possessed a configuration similar to that 

 roughly indicated in one plane by either of the above formulae, 

 upon reduction to a monobasic acid there would be an equal 

 number of chances of each of the two end carboxyl groups being 

 attacked by the reducing agent and converted to CH„OH 

 groups. Consequently it was to be expected that equal quanli- 

 NO. II 75, VOL, 46] 



ties of two geometrically isomeric monobasic acids would be 

 obtained, one dextro- and the other Isevo-rotatory, Such has, 

 indeed, been found by Prof Fischer to be the case ; for, upon 

 reducing cither the ethyl ester or the lactone of mucic acid (the 

 acid itself being unattacked) by means of sodium amalgam, an 

 optically inactive acid of the constitution CH20H—(CHOH)4— 

 COOH was obtained, which formed a salt with strychnine 

 yielding two distinct kinds of crystals, resembling the well- 

 known complementary racemates of Pasteur. From these two 

 kinds of crystals solutions of the free acids were obtained, which 

 were respectively dextro- and laevo-rotatory, and each was aijain 

 converted into mucic acid upon oxidation. One of these, the 

 right-handed variety, was identical with the common galactonic 

 acid prepared by oxidation of galactose. Moreover, by further 

 reduction of the inactive acid, an inactive glucose was obtained, 

 from which eventually common dextro- and also leevo-galactose 

 were isolated by fermentation ; and finally, by still further reduc- 

 tion of the galactose, dulcitol itself was obtained. Hence, the 

 symmetrical structure of the dulcitol group may be considered as 

 proved, and the work also completes the artificial synthesis of 

 these compounds ; for, given the synthesis of any one by the 

 method previously described by Prof. Fischer, any of the others 

 may be prepared from it by the processes now described. 



The additions to the Zoological Society's Gardens during the 

 past week include a Rhesus Monkey {Macacus rhesus) from 

 India, presented by Miss Beatrice Raymond ; a Wild Swine 

 {Sus scrofa 9 ) from Tangiers, presented by Mr. E. H . 

 Banfalher ; a Great Kangaroo {Macropus giganteus) from 

 Australia, presented by Mrs. Frazer ; a Purple Heron {Ardea 

 purpurea), European, presented by Captain Woodward ; a 

 Bateleur Eagle {Helotarsus ecaudatus), a Tawny Eagle {Aquila 

 ncevioides) from Africa, presented by Captain Webster ; a Raven 

 {Corvus ^(?;-«jr), European, presented by Mr. F. J. Stokes; 

 seven Common Vipers ( Vipera berus), British, presented by 

 Mr, T. A. Cotton, F.Z.S. ; a Rufous-necked Weaver Bird 

 {Hyphantornis textor) from West Africa, purchased ; an 

 English Wild Bull ^Bos taurus), born in the Gardens. 



OUR ASTRONOMICAL COLUMN. 



Sun-spots. — In the March number of the Memorie delta 

 Societii degli Spettroscopisti Iialiani, there are some interesting 

 notes relating to spots and prominences. Prof. Tacchini gives a 

 tabulated statement of the solar observations made at the Royal 

 Observatory for the last three months of the year 1891. The 

 most frequent records of faculse occurred in the zones ± 10° ±30°, 

 only one being seen as high as the zone -f 40° -f 50°. As 

 regards the spots, the greatest frequency of groups took place in 

 the zones ± 10° ± 20°, 23 and lo being observed in the north 

 and south respectively. 



Profs. A. Mascari and J. Fenyi both contribute some notes 

 on the large group of spots visible in February last, the latter 

 pointing out that the relation of the eruption to the large group 

 was such that its centre was situated very near the side of the 

 great nucleus of the south spot, but was entirely outside the spot 

 itself. 



M, H, Deslandres records also his observations with respect 

 to the remarkable protuberance visible on March 3 at about 

 10 a.m. From spectroscopic observations he obtained a radial 

 velocity of 200 kilometres per second, using the hydrogen and 

 helium lines. He also obtained a photograph of the invisible 

 ultra-violet region, which furnished him with "an exact image" 

 of this protuberance. The H and K lines were extraordinarily 

 brilliant, and the negative contai. ed the entire series of ultra- 

 violet rays of hydrogen. It may be mentioned that at the ap- 

 pearance of this large protuberance no special indication was 

 registered on the curves of the magnetic instruments which M, 

 Deslandres obtained from M. Wolf. 



Pro*", Tacchini communicated to the Paris Academy on 

 April 25 the results of solar observations made at the Roman 

 College (luring the first three months of this year. Spots and 



