March 22, 1888] 



NATURE 



503 



whose compounds are invariably coloured, the greatest diversity 

 of colouring is often noticealjle among the several compounds 

 of one and the same element — as in those of chromium or man- 

 ganese, for example : it is therefore clear that colour is in a high 

 (legree conditioned by special fornix of intramolecular structure, 

 and consequently that any attempt to determine the "origin of 

 colour" must be based on a knowledge of the structure of coloured 

 matters. For this reason it has become possible only within 

 recent years to discuss the relation between colour and con- 

 stitution, and, so far, the discussion has been limited to two 

 papers by Graebe and Liebermann (>9tv'. detit. cliem. Gesellsch., 

 1868, 106) and by Witt (ibid., 1876, 522) respectively. To 

 illustrate the idea on which the argument in the paper is based, 

 the author compares the unsaturated hydrocarbons with the 

 paraffins. In the paraffins, which are singularly inert com- 

 pounds, and all but colourless even in the infra-red and ultra- 

 violet regions of the spectrum, the carbon atoms are united only 

 by single affinities, and the remaining affinities are engaged by 

 monad atoms ; the unsaturated hydrocarbons, however, are not 

 only more reactive than the paraffins, but the beginnings of 

 colour are manifest in them in regions above and below the 

 visible spectrum, whilst they are conventionally represented by 

 formula' in which the carbon atoms appear as united by two or 

 three affinities of each, typified by straight lines or dots. Within 

 recent years, however, the idea has found favour that "affinity 

 has direction," and the author would apply this hypothesis 

 to polyad atoms gener^illy ; and in formulating compounds in 

 which such atoms are united by more than single affiiiites, would 

 represent the polyad atoms as united by curved lines in order to 

 suggest that the affinities are under strain in consequence of their 

 being free to act only in certain directions. In the paper, the 

 author cites a number of cases among inorganic compounds 

 which he thinks affiDrd evidence that the production of colour is 

 dependent on special modes of atomic arrangement, and parti- 

 culai-ly on such modes of arrangement as involve the existence 

 of a condition of strain in the resulting system, due probably to 

 peculiarities in the affinity relationships of the c mstituent 

 elements of the system which prevent complete mutual neutraliza- 

 tion of the affinities. The occurrence of colour therefore is more 

 frequently than not concomitant with a high degree of reactivity, 

 the coloured compound being usually one of "high potential" 

 or slight stability. Among carbon compounds there is no in- 

 stance of a hydrocarbon being coloured, giving the term its con- 

 ventional meaning ; and omitting nilro-compounds, there are 

 very few exceptions to the rule that derivatives of hydrocarbons 

 containing only monad radicles are colourless ; the exceptions, 

 moreover, are of a very noteworthy chxracter, being either 

 central derivatives of anthracene, i.e. compounds formed liy 

 displacement of the hydrogen atoms of the central nucleus 

 of anthracene — which although not coloured is significantly 

 fluorescent ; or the monad radicle contains at its origin a radicle 

 such as CO. Attention is then drawn to the quinones and their 

 derivatives, I\ittig's ketone formula being throughout adopted 

 for these compounds. The constitution of the better-known 

 dye-stuffs is then discussed, and the author is led to conclusions 

 which in some cases are different from those hitherto accepted ; for 

 example, the azo-dyes are formulated O^CfiHj^N.NHR' and 

 IIN^CgHj^N.NlIR'; androsaniline with its congeners, certain 

 of the phlhaleins, and methylene-blue are also formulated on the 

 quinone type. In the discussion on the paper, in which Profs. 

 Debus, Riicker, and Dewar, Dr. Morley and others took part. 

 Prof. G. C. Foster said that it appeared to him that the real 

 cjuestion raised by Dr. Armstrong was whether a definite re- 

 lation could be traced between chemical composition or chemical 

 structure and the existence and position of absorption-bands in 

 the .spectrum of the transmitted radiation. The presence or 

 absence of coloration, as it could be judged of directly by the eye, 

 gave no conclusive answer to the question, for a substance might 

 be as colourless as water, and stdl exert strong absorption in 

 the ultra-red, or it might have strongly-marked absorption in 

 the ultra-violet. But, more than this, a body might exert 

 selective absorption within the visible spectrum, but if it 

 happened to absorb two complementary colours it would be 

 judged of by the eye as though it were destitute of selective ab- 

 sorption altogether. The subject, therefore, seemed to him to 

 involve a systematic study of absorption-spectra. — Researches on 

 chromorganic salts. Part II., by Mr. E. A. Werner. — Note on 

 benzyldithiourethane, by Dr. A. E. Dixon. 



Zoological Society, March 6. — Prof. Flower, F.R.S., 

 President, in the chair. — The Secretary read a report on the 



additions that had been made to the .Society's Menagerie during 

 the month of Februaiy 1888, and called special attention to 

 some examples of a Finch from New Caledonia {Erythrura 

 psittacea), and to five specimens of a Pheasant {Phasianus 

 principalis) from Afghan Turkistan. The pheasants had been 

 brought home and presented by Major Peacock, R.E., of the 

 Afghan Frontier Commission, at the request of Sir Peter Lums- 

 den, G.C.B., C.S.I.— The Secretary exhibited (on behalf of 

 Lieut. -Colonel II. M. Drummond Hay) a specimen of the 

 De-ert Wheatear (Saxicola deserti), lately killed in Scotland. — 

 A paper by Prof. G. B. Howes and Mr. W. Ridewood, on the 

 carpus and tarsus of the Anura, was read. The authors re- 

 corded observations made upon thirty-seven genera and sixty 

 species, in all stages of development, representatives of all but 

 three or four less important families. The authors were at 

 variance with previous writers in points which had necessitated 

 a reconsideration of the morphological value of the leadin|^ 

 elements of both carpus and tarsus. They had failed to dis- 

 cover, at any stage, a trace of a third proximal element in either 

 fore or hind foot, while they showed that Born was in error in 

 regarding the navicitlarc as the prehallux tarsal. In the hind 

 foot they recorded the discovery of a fourth tarsal, and in the 

 fore fojt that of a fifth carpal, which latter in Xcnophrys was 

 bony. Consequent upon this they regarded the element hitherto 

 held to be the fifth carpal as a postaxial centiale ; whence it 

 followed that the Anura are, as a group, unique in the posses- 

 sion throughout of a double ccntrale carpi. The authors dis- 

 cussed the various changes undergone by the pollux and pre- 

 hallux, and the several views concerning the morphological value 

 of the latter. A second part was added, in which the peculiari- 

 ties of the several families of the Anura were given in order, 

 and the bearings of the structures in question upon classification 

 briefly discussed. The Discoglossidee were shown to combine 

 most completely the least modified conditions of both fore and 

 hind feet. — Mr. R. Bowdler Sharpe read descriptions of new 

 species of birds, of which specimens had lately been received 

 from the Island of Guadalcanar, Solomon Group, collected by 

 Mr. C. M. Woodford. These were named Astnr Jiolomclas, 

 Astur woodfordi, Asliir shebce. Baza giiadalcanarcnsis, Ninox 

 granti, Graticahts liololins, Edoliisoma erythi'opygiiim, and 

 Poinarea erythrosticta. — Mr. W. R. Ogilvie Grant contributed 

 a complete list of the birds obtained by Mr. Woodford on the 

 Islands of Guadalcanar and Rubiana. These were altogether 

 sixty-six in number, the new ones being Nasitcrna aoht, Alyzo- 

 Icma sharpii, Phlcga-nas solonionensis, Ardciralla ivoodfordi, and 

 Nycticorax mandihularis . 



Entomological Society, March 7. — Dr. D. Sharp, Pre 

 sident, in the chair. — Mr. J. H. Leech exhibited, and made- 

 remarks on, a number of butterflies forming part of the col- 

 lection made for him last summer by Mr. Pratt, at Kiukiang, 

 Central China. The specimens exhibited included Papilio 

 Macilcntiis, hitherto only recorded from Japan, varieties of /', 

 Sarpedon, and a supposed new species of Papilio ; a series of 

 Sericinns telamon ; Charaxes narcittts, and var. man iar inns ; 

 PalcEoiympha opalina ; new species of Lethe, Apatura, and 

 Neptis ; and a series of Argynnis paphia, with the var. valaina 

 of the female. Mr. Leech stated that all the females of A. 

 paphia taken at Kiukiang belonged to the var. valczina, the 

 typical form of the female being unknown there. Mr. Poulton 

 expressed his interest in Mr. Leech's statement that valczina was^ 

 the only form of the female of Argynnis paphia known at 

 Kiukiang, and said he considered this fact would probably throw 

 a new light on the question of the dimorphism of the species. 

 Mr. Jenner-W^eir said he had in the course of some years ob- 

 tained a series of forms intermediate between the typical female 

 and the variety valczina. Mr. H. Goss, Dr. Sharp, and Mr. 

 McLachlan, F. R S., continued the discussion. — Mr. Champion 

 exhibited, for Mr. J. J. Walker, R.N., about 950 species of 

 Coleoptera, recently collected by the latter near Gibraltar. Mr. 

 McLachlan called attention to the large number of water-beetles 

 included in Mr. Walker's collection. — Mr. Verrall exhibited, 

 living specimens of Aspidomorpha sancta-cnicis, from the caves- 

 ofElephanta. — Mr. Slater exhibited specimens of a species of 

 weevil which had been doing much damage to maize sent to the 

 Colonial Exhibition. — Mr. W. White read a paper entitled " Ex- 

 periments upon the colour-relation between the pupae of Picris 

 rapcc, and their immediate surroundings," which comprised a de- 

 tailed accoimt of aseriesof observations carried on at the author's 

 instigation by Mr.. G. C. Griffiths. The various experiments were 

 intended to act as a test of the conclusions arrived at by Mr. 



