236 



KNOWLEDGE. 



June, IQll. 



appeared to be perfectly mature, except that the wings were 

 shorter than the body, as is usual when the insect first bursts 

 from the pupa case. It had often been a matter of conjecture 

 how it was that when the wings of a butterfly were fully 

 expanded a few hours after emergence, the scales were all 

 perfectly formed and covered the entire wing surface by over- 

 lapping at their lower edges like tiles when laid on the roof of 

 a house. It did not seem possible that if the scales were 

 fully formed an5 covered the wings in the same manner when 

 only one third of their ultimate length, they could also cover 

 the expanded wing so completely as we find to be the case in 

 the mature insect. On setting the specimen referred to, and 

 placing it under the microscope, the mystery was at once 

 sohed by finding that the scales were all there and in perfect 

 condition, but instead of lying fiat they were standing on end 

 attached to the membrane of the wing in the usual manner, 

 but so close together that the coloured pattern formed by them 

 could be distinctly made out. In this position, — just as 

 roofing tiles take up less room when standing close together on 

 edge, — the scales then occupied a niinimum amount of space, 

 and it seemed clear that as the membrane expanded it would 

 draw their stalks farther apart, and at the same time cause 

 them to lie down, and in this way cover a greatly increased 



^^"^^^ . . R. T. Lewis. F.K.M.S. 



THE ROYAL MICROSCOPICAL SOCIETY.— April 

 19th. H. G. Plimnier. Esq., F.R.S., President, in the chair. 

 Mr. E. J. Spitta gave a demonstration of low-power photo- 

 micrography with special reference to colouring methods, 

 in which he showed some fifty coloured slides which had 

 been coloured by an artist friend by a completely new method. 



Mr. Spitta also communicated a report on Grayson's 

 Rulings presented by Mr. Conrad Beck to the Royal Micro- 

 scopical Society, which embodied the results of many thousand 

 observations. 



Mr. E. J. Shepherd read a paper on "The Re-appearance 

 of the Nucleolus in Mitosis," which formed an addendum to 

 his previous paper, communicated in April, 1909, on "The 

 Disappearance of the Nucleolus in Mitosis." In the present 

 connnanication he said that with a view to ascertaining how 

 and when the nucleolus makes its re-appearance, the diaster 

 stage is the one which calls for most careful study and 

 observation. At or about the time of the formation of the 

 dispirem, and before the diasters have lost their characteristic 

 shape, a looping in the chromatin is observed — the number of 

 loops varying in each daughter nucleus. It is in these loops 

 that the nucleoli will appear, but it must not be inferred that 

 a nucleolus will appear in each loop, as there are frequently 

 more loops than nucleoli. The latter make their appear- 

 ance when the division of the cell is well marked, and 

 when the interzonal fibres have generally disappeared. 

 From the results of his research, he was of opinion that the 

 nucleolus is a product of the chromatin injected into the loops 

 by a process which can best be described as a "streaming in " 

 process. A full account of the technique of the staining and 

 methods adopted, and so on, which have led to the above 

 conclusion, will be found in the Jniinia! of the Royal 

 Microscopical Society. 



Mr. J. Murray communicated the second portion of a report 

 from the Shackleton Antarctic Expedition of 1909, on the 

 Canadian Rotifera. Forty-two species (all Bdelloids) were 

 collected among mosses. They included five new species — 

 Calliditia aspcnila, C. canadensis, Mniobia obtiisicornis, 

 M. inonfiiiiu. Habrotrocha inaculata. There were also a 

 number of peculiar varieties of other species. C. aspentla 

 has since been found in Ireland by the Clare Island Survey. 

 Twenty-seven Bdelloids were previously recorded for the 

 United States. Six of these occurred in their collections, so 

 that the number of Bdelloids now known in North .America 

 stands at sixty-three species, but a number of these are of 

 doubtful value. .Among the rarer Canadian species were 

 I'liilodina austral is (.•\ustralia and Canada), Callidina 

 speciosii (British Guiana and Canadal. C. zickendrahti 

 (Russia and Canada). 



.A description of a new piece of apparatus for photomicro- 

 graphy, with the microscope in the inclined position by Sefior 

 Domingo de Oureta, was read by the Secretary. 



OUEKETT MICR(JSCOPICAL CLUB. — April _',Sth. 

 1911. Professor E. A. Minchin, M.A.. F.R.S., President, in 

 the chair. Dr. .\. C. Coles, of Bournemouth, sent a note 

 describing the advantages of Parolein as a mounting medium. 

 Its refractive index is 1-471, as against 1 -530 for balsam in 

 xylol. It is absolutely neutral, and. so far as is known at 

 present, is entirely without action on any dyes. It is rather 

 more trouble to use than a balsam, as, being a liquid, the 

 preparations require to be ringed with some cement which is 

 also neutral. (A detailed account of the methods employed 

 by the author will be found in The Lancet for April 1st, 

 1911.) A number of bacterial preparations mounted in 

 parolein were exhibited under microscopes lent by Messrs. 

 H. F. Angus & Co. 



The President exhibilinl and described: (1) Cysticercoid 

 of the rat-tapeworm Hynienolcpis diminnta from the 

 body-cavity of the rat-flea, Ceratopliylliis fasciatns, with 

 head invaginated. (2) The same, with head extended. 

 (3) Another species of cysticercoid, probably H. miiriiia. also 

 from the body-cavity of the rat-flea. (4) Ventral nervous 

 system of C. fasciatits. (5) Salivary gland and duct of 

 C. fasciatns. These preparations were displayed under 

 microscopes, also kindly lent by Messrs. H. F. .Angus & Co. 



The Honorary Treasurer. Mr. F". J. Perks, read "Some Notes 

 upon Seeds as Micro-Objects " contributed by Mr. N. F,. Brown. 

 It was reconnnended that the specimens be mounted in cells, dry, 

 on clear glass slips, not on a dark ground, and fixed in position 

 with seccotine or gum. For illuminating, a spot lens and 

 concave mirror below the stage, together with a stand 

 condenser to give top light, were used. Added beauty is 

 obtained if coloured gelatine, say red, is placed below the 

 spot-lens, and a green gelatine held over the stand-condenser. 

 Some of the more beautiful varieties w-ere then described, 

 among which may be mentioned Pterospernia andrunicdea, 

 Paiiloxoiia iniperialis. Philydrnni lanuginosnm, Nemesia 

 StriDuosa, Elioinirus elegans, and Sesantum capense. 



Mr. D. J. Scourfield. F.Z.S., F.R.M.S., made some remarks 

 on " The LIse of the Centrifuge in Pond-Life Work." He had 

 recently been experimenting with a hand-driven form running 

 at about seven thousand revolutions per minute. The tubes 

 held only about one-and-a -half c.c. instead of the usual fifteen c.c. 

 It was found that if plain water be taken from any pond in a tube 

 without a net. and centrifuged, there are obtained numbers of 

 very minute flagellates, very small heliozoa, diatoms and 

 desmids, and a great variety of immature forms. The size of 

 these organisms was of the order of the one-thousandth of an 

 inch (25m). There was a considerable field for work on what 

 had been christened the " centrifuged plankton." He had 

 observed quite a number of forms new to him. but could not 

 yet say if they were really new. Certainly some of them had 

 never been named. 



ORNITHOLOGY. 



By Hugh Boyd Watt, M.B.(.).U. 



JUDGMENTS ON THE KOOK. — Mr. Walter E. 

 CoUinge has recently been investigating the feeding habits of 

 the rook, and gives his finding in his First Report on 

 Economic Biology (Birmingham, Midland Educational Coy., 

 1911. Price 2, 6 net.) He is strongly of opinion that we have 

 too many rooks, as they are distinctly destructive to cereal 

 and root crops, game, and so on, and that they should be 

 systematically reduced in number and held in check. This 

 verdict is supported by the results obtained from examination 

 of the stomach contents of eight hundred and thirty rooks 

 shot throughout the year 1908-9. in England and Wales, and 

 (to continue using Mr. Collinge's own words) showing: — 



(1) That 67-5 per cent, of the food of the rook consists of 



grain ; if to this we add that of roots and fruits, the 

 percentage is raised to 71 per cent. 



(2) The animal food-content was only about 29 per cent., of 



which quite one-third must be reckoned against the rook. 



