116 



KNOWLEDGE. 



March. 1911. 



Society from the Gold Coast, there emerged a crowd of youn.t; 

 mantids. about four milUuietres in length, which. ""uhen crawling 

 about the case, looked exactly like a crowd of black ants, their 

 rapid darts and -pauses recalling irresistibly the busy method 

 of progression so characteristic of these Hymenoptera." Mr. 

 R. I. Pocock. the Superintendent of the Gardens, observed them 

 carefully, and noticed that it was only when in motion that 

 they resembled ants. When at rest they were seen in their 

 true colours — as Mantises. "raising the fore part of the body 

 and head, folding up their fore-legs, and every now and then 

 swaying gently from side to side, as if rocked by the wind. 

 While thus employed they were seen to be procryptically 

 coloured.'" That is to say, they were inconspicuous. Mr. 

 Pocock has analysed the resemblance to an ant. and finds that it 

 is p.artly due to the blackness of the underside of the abdomen, 

 and partly to the habit the moving insect has of curling the 

 posterior half of the abdomen up like a scorpion's tail. This 

 altered the proportions and shape, and in a curious way a 

 white spot on the prothorax simulated an ant's waist. When 

 the young insects attained a length of se\en millimetres they 

 lost their ant-like look. Mr. Pocock also directs attention to the 

 conspicuous larva of a Ceylonese leaf-insect, closely resembling 

 a distasteful beetle I Lycostoiuus gcsfroiK which is also 

 mimicked by two bugs and a motli. 



COPEPODS .\XD ALCYONAKI.AXS. — Colonies of 

 Alcyonarians often harbour small parasitic Copepods. which 

 are known as Lamippids. They are very distinctive little 

 creatures, characteristic in their buccal armature at one end, 

 and in their caudal fork at the other. They have been recentlv 

 studied systematically by A. de Zulueta. and the result shows. 



what is so often true of parasites, that each species of Lamippc 

 has its particular host. Some hosts may harbour two or 

 three species, but no species occurs on two different hosts. It 

 is impossible not to wonder whether in these cases, and for 

 others like them — Xematode worms, for instance — there may 

 not be "modification species." whose characters are directly due 

 to their immediate environment. It would be interesting to trans- 

 plant some young Lamippids from one Alcyonarian to another. 



SIMULACRA VITAE.— If a weak solution of gelatine is 

 spread on a slide and tiny drops of ferrocyanide of potassium 

 are put on at intervals of five millimetres by means of 

 a pipette, beautiful simulacra of nucleated cells are produced. 

 If fragments of calcium chloride are dropped into sixty grains 

 of silicate of potassium at thirty-three degrees, sixty grains of 

 saturated solution of carbonate of soda, thirty grains of 

 saturated di-basic phosphate of soda, and distilled water up 

 to a litre, then beautiful phantasms arise — " osmotic growths " 

 — like mushrooms and moulds and corals and shells. 

 Professor Stephane Leduc has given much time to these 

 interesting and fascinating simulacra vitae. and discusses 

 their importance in a recent book (" Theorie Physico- 

 Chimique de la Vie." Poinat, Paris, 1910). There are. of 

 course, osmotic phenomena in organisms, and the more they 

 are studied the better, but it appears to us to be giving an 

 entirely false simplicity to the facts to declare that biology 

 is a subdivision of the physico-chemistry of fluids. This is 

 a survival of the discredited materialistic superstition, and 

 to credit the artificial osmotic growths with nutrition, 

 assimilation, irritability, and a power of development, is a 

 bad instance of an assertion that outstrips its evidence. 



THE LEONID FIREBALL OF NOVEMBER i6th, 1910. 

 Bv W. F. DENNING. F.R.A.S. 



The Moon being full at the epoch of the Leonid shower in 

 1910, it appears to have been but slightly observed. .A very 

 brilliant member of the stream was, however, seen by various 

 persons who were watching the total lunar eclipse on the night 

 of November 16th. 



Mr. J. Cranston, of Giffnock, near Glasgow, saw the meteor 

 at 12" 27". It fell from a few degrees to the right of Algol, 

 almost vertically downwards, bursting in Andromeda. The 

 direction was from between Capella and L'rsa Major. It left 

 a tail visible for se\era! minutes. The length of path was 

 about 26 , and when bursting the meteor appeared to equal 

 the size of the moon. 



Mr. W. B. Ogilvie, at Greenock, N.B., gives the time as 

 12*' 26". He saw an intensely luminous streak stretching 

 from above the stars, 35, 39, 41 Arietis towards Capella. The 

 streak was broken and the brighter portion lay west of 

 Capella. It was visible to the unaided eye for five minutes. 



Miss Helen M. Metcalfe recorded the meteor at Kildare, and 

 Miss Rose Atkinson from Pitlochry, while correspondents to 

 the English Mcchtjiiic also described its appearance. 



There is no question but that the meteor was a brilliant 

 Leonid passing over Scotland and the north coast of Ireland. 

 Its height was from ninety-one to forty-five miles. The radiant 

 point was near 150°-|- 23° in the well-known "Sickle of Leo." 



At and near Glasgow the fireball presented a splendid 

 appearance, and the intense light accompanying its sudden 

 outburst astonished many persons. The apparition of this 

 fine Leonid is interesting as proving that the shower returned 

 in 1910, though possibly under a feeble aspect. Thirty- 

 three years ago, viz., in 1877, November 10th to 13th. I 

 recognised it, but it was very feeble. 



Tempel's parent comet of the Leonids is now not %ery far 

 removed from its aphelion outside the orbit of L'ranus. Such 

 meteors of this stream as are noticed during the few forth- 

 coming years will, therefore, be at nearly the opposite part of 

 the orbit to the comet. It is known, how-ever, that the stream 

 is an annually visible one, and that the meteors are distributed 

 right around the ellipse, though only feebly so in certain 

 sections of it. 



Mr. J. McHarg. of Lisburn, near Belfast, reports that at 

 midnight (Dublin time) he observed a bright flash, and looking 

 towards the stars of Ursa Major he remarked a short, broken 

 meteor-streak, about 1° above the stars S and 7. The direction 

 of this streak was from the radiant of the Leonids, and a 

 small Leonid shooting star passed through Ursa Major at the 

 time the streak from the fireball was suspended there. It 

 remained three minutes, the portion near the star S Ursae 

 Majoris mo\ing downwards to below 5, while the westerly 

 section formed a small patch of nebulosity, and continued 

 stationary about 1 above 7. 



The position of the streak was evidently influenced by air 

 currents of different velocities and directions in the upper 

 regions of the atmosphere. The singular streak left for three 

 hours by a fireball on February 22nd, 1909, exhibited similar 

 phenomena ; while the ends appear to have retained nearly 

 the same position for the long time, the central parts drifted 

 N.W. at the velocity of ninety or one hundred miles per hour. 



Mr. C. L. Brook, of Meltham. near Huddersfield. obtained 

 an excellent view of the fireball, and as he is an experienced 

 and accurate meteoric observer his record is of special value. 

 He places the beginning of the luminous course in the region 

 of a Draconis and the whole path as from 205° + 60° to 

 295°+3S°. The meteor burst at 293"-4-44= 20' and a small 

 section of the streak remained visible without drifting much 

 for five minutes. The meteor ended with a minor explosion 

 before it reached v Cygni. 



In deducing the height and length of path of the object, I 

 have had to revise some of the observations. I think the 

 best real path obtainable is that the meteor passed over the 

 sea near Berwick, to nearly above Edinburgh and Glasgow, 

 and westwards over Kintyre, ending north of Rathlin Island 

 off" the north coast of Ireland. Several of the observers 

 place the end further west, while Mr. Brook's record indicates 

 that it began earlier in its flight and decidedly east of Berwick. 

 However, a length of flight of one hundred and sixty-five 

 miles and a velocity of thirty miles per second satisfies the 

 observations and cannot well be far from the actual course. 



