66 



NATURE 



[November 9, 191 1 



SOCIETIES AND ACADEMIES. 



London. 



Royal Society, November 2.— Sir Archibald Geikie, 

 K.C.B.. prisidont, in th<- rhair.— Sir \V. dc W. Abney : 

 Colour-btiiKltiess and llit- trichromatic theory of colour- 

 vision. Tart iii. — Incompletf colour-blindness. 'Iho first 

 part of the paper shows how, if an equation be formed by 

 rays in known position in the spectrum to match a white, 

 by normal vision and by the colour-blind, the two can be 

 compared together without special reference to the 

 luminosity of the matched white. The luminosities of all 

 the rays are known in the one case, and only two in the 

 second, and from the two matches the unknown deficiency 

 of colour sensation can be calculated. Owing to the fact 

 that large quantities of their white can be mi.\ed with the 

 colours without being detected by those incompletely colour- 

 blind who have a small factor for one of their sensations, 

 a very false interpretation of their colour-blindness might be 

 arrived at by the method described above. If, however, 

 the luminosity of the composite white and the matched 

 white be carefully equalised, a full determination of the 

 colour deficiency can be arrived at by treating the equation 

 somewhat in the manner described in part ii. of this same 

 subject, when a true result is obtained. The latter part 

 of the paper dealt with colour equations made from the 

 rotation of discs ; and it is shown that trustworthy results 

 can be obtained from their use so long as the sensations 

 stimulated by the pigments in the light in which they are 

 viewed are known in amount. The method of ascertain- 

 ing the sensation composition of the pigments, and of the 

 light used for their illumination, is described. When once 

 these are known, no further appeal to the spectrum is re- 

 quired. The author recommends the use of a white light 

 passing through a yellow substance, such as chromate of 

 potash solution, as a viewing light, in which only the red 

 and green pigments are required in the inner disc, the 

 blue not being wanted. The " grey " match becomes thus 

 much brighter and is easier to read. — H. R. A. Mallock : 

 Note on the iridescent colours of birds and insects. In 

 this note reasons are given for the view that certain forms 

 of brilliant coloration which occur in the feathers of birds 

 and in the scales and integuments of insects are due to 

 interference, and are of the nature of the colours of thin 

 plates. Walter, in 1895, in Germany, and quite recently 

 Michelson in America, have written on this subject, and, 

 basing their opinions on the behaviour of polarised light 

 when reflected from the colour-producing surfaces, conclude 

 that the colours are due to selective absorption and reflec- 

 tion, and are akin to those reflected from certain anilin 

 dyes and from metals. The reasons against this view 

 and in favour of interference are (i) that when any of 

 these natural colour-producing structures are penetrated by 

 a fluid having the same refractive index as that of the 

 material of which the structure is composed, the colour 

 disappears ; (2) when the refractive index of the fluid is 

 less, the colour does not disappear altogether, but changes 

 towards the red ; (3) (which is perhaps the most important) 

 under mechanical pressure the colours first change towards 

 the red and then (as the pressure increases) disappear. 

 These results are what might be expected from a structure 

 which produces interference, and it is difficult to reconcile 

 them with any other hypothesis. The note is founded on 

 observations, extending over many years, on examples of 

 this class of colour production taken from a considerable 

 number of orders and genera, both of birds and insects, 

 and the methods of examination employed are shortly 

 described. — K. R. Lowin : The behaviour of the infusorian 

 micronucleus in regeneration. When Stylonychia mytilus 

 is cut in two, so that each merozoon receives one member 

 of the meganucleus and one micronucleus, both fragments 

 exhibit in favourable circumstances complete regeneration. 

 This involves segmentation of the meganuclear member 

 and division of the micronucleus. If a portion of the 

 cytoplasm be removed from the hind end of the animal 

 without disturbing the nuclei, there may occur during 

 regeneration a division of one, usually the posterior, micro- 

 nucleus. The result is to furnish the regenerated 

 infusorian with three micronuclei instead of two, i.e. the 

 division does not restore, but actually disturbs, the nuclear 



relations characteristic of the race. When the regenerated 

 NO. 2193, VOL. 88] 



individual proceeds to fission, all three micronuclei divi. 

 That an extra division can be introduced into th« 

 cycle of mitoses shows that the organella is in a 



to divide before the whole animal is ready for spom ^, 



fission ; that the supernumerary mitosis occurs during 

 regeneration suggests that the stimulus causing the micro- 

 nucleus to divide may be the condition of the surround: 

 cytoplasm which obtains during the constructive activi' 

 of regeneration. The cases in which regeneration oc< 

 without either of the micronuclei dividing can be supp<< 

 to be those in which either the micronuclei were not 1 

 for mitosis or the stimulus was not suflTiciently intons<^ 

 evoke a division — by reason, e.g., of regeneration oci 

 ring slowly, with no great intensity of constructive jr 

 cesses at any time. At the normal fission of the .nnin 

 when all the micronuclei present divide, there is n 

 formation of new parts quite comparable with the ' 

 activity in regeneration, and accomplished, it is natural^ 

 suppose, with much the same condition of the cytopla 

 The normally occurring mitoses, and those taking pli 

 during regeneration, can thus Ije brought under one 

 of view. — A. F. Hayden and W. P. Moraran : An inqtj 

 into the influence of the constituents of a bact 

 emulsion on the opsonic index. These experiments, so 

 as they have gone, show that in the technique of 

 estimation of the tubercle opsonic index the quantity 

 character of the contents of the bacterial emulsion 

 be taken into account, and that the chief factor influenc 

 the estimation is the finely ground bacterial detritus res 

 ing from the process of triturating the dried culture of 

 bacillus. — Colonel Sir David Bruce : The morphology 

 Trypanosoma gatnbiensc (Dutton). — A. H. Caulfeil 

 (i) Factors in the interpretation of the inhibitive 

 fixation serum reactions in pulmonary tuberculc 

 (2) preliminary report upon the injection of rat 

 with protein-free (tuberculo-) antigen and antigen-sef 

 mixtures. 



Phvsical Society. October 27.— Prof. H. L. Caller 

 F.R.S., president, in the chair. — Hon. R. J. Str» 

 Further observations on the afterglow of electric discha 

 and kindred phenomena. It is shown that ozone prepar 

 by means of the Siemens ozone tube used at atmosph 

 pressure is able, when mixed with nitric oxide, to give 

 greenish-yellow afterglow flame. This result is c 

 attained, however, when the ozone has been concentrj 

 by fractional distillation. A blue glow is obtained u« 

 the same conditions with sulphuretted hydrogen and oz 

 The effect of sulphur compounds in improving the 

 glow noticed by the older experimenters is shown to" 

 due, not to any direct intervention of these bodies in 

 reaction, but to their power of destroying organic mat 

 prejudicial to ozone. When once this is got rid of, 

 sulphur compounds are of no further advantage. It 

 found that pure oxygen does not give an afterglow, 

 afterglow seen in electrodeless bulbs containing oxygen^ 

 due to some interaction with water vapour. ~" 

 luminosity given out when ordinary spring water is shs 

 with ozone is shown to be due to oxidation of peaty mj 

 contained in it. Brown peat water gives greatly enhal 

 luminosity. — Prof. C. G. Barkia and J. Nicol : H( 

 geneous fluorescent X-radiation of a second series, 

 was shown by one of the writers that the fluores 

 X-radiations emitted by elements exposed to prir 

 Rontgen radiation can be arranged in series, one ra 

 tion in a particular series being emitted by each eler 

 and the radiation belonging to that series becoming 

 penetrating with an increase in the atomic weight of 

 radiating element (Proc. Camb. Phil. Soc, May, i< 

 The homogeneity of radiations of only one series (thej 

 series) was shown by Barkia and Sadler. This 

 describes experiments showing the homogeneity of 

 escent X-radiations in the second series (the L series), 

 exhibiting the homogeneity of radiations of the two s 

 from a number of elements. Details are given of uic 

 observations on the radiations from barium. Similar 1 

 results are recorded in the case of the radiations from ; 

 iodine, antimony, and silver. The homogeneous fluorescent 

 radiations of different series are emitted simultaneously by 

 an element exposed to Rontgen radiation of more pene- 

 trating type than either. The fluorescent X-radiations cao 



