May II, i8v^3j 



NATURE 



29 



%vish to draw attention to it — all the more since so competent 

 writer as " D. H. S." seems in a review in Nature (April 

 7) to be unaware that the theory of variation by amphimixis ' 

 jias ceased to exist as a " Difficultv in Weismannism." 

 Cork, May I. ' Marcus Hartog. 



Medical Biology. 



G. B. H. HAS, I am glad to sec, criticised effectively the 

 yllabus of Elementary Biology put forth by the Conjoint Board 

 Nature, vol. xlvii. p. 530). A less fortunate course of study could 

 Jardly have been devised. The students who take the course 

 'nclude a number whose previous education, energy and ambition 

 ire not sufficient to encourage them to attempt a university 

 i:our.'ie, and the average quality is therefore not very good. They 

 Vork through a number of unicellular types, which give no 

 raining for the hands, though they are no doubt useful in other 

 ivays. Then come Hydra and the Leech. Hydra is of course 

 I good subject. The Leech is not instructive to a student who 

 las no knowledge of similar animals, and the untrained man 

 •cannot possibly dissect it for himself. The rest of the course 

 J;onsists of parasitic worms and certain generalities. The parasitic 

 worms commonly have the nervous system, heart, and some- 

 imes even the alimentary canal absent or poorly developed, 

 *hile the reproductive organs are of extraordinary complexity. 

 I'^rom these the student has mainly to derive his notions of the 

 plans of structure which are found among animals. Such a 

 ;ourse of study looks practical, but it is almost pure waste of 

 ime. It does not teach the student to dissect, nor does it 

 ntroduce him to those problems of Nature which are most 

 ^sible to a beginner. In fact, the whole course may be 



tted to evaporate shortly, leaving behind nothing more 



ible than a recollection of the outward appearance of 



in parasitic worms. 



hen the teacher attempts to introduce more instructive 

 -11! jects, the class, solely bent upon satisfying the Conjoint Board, 

 ire too apt to scamp the work, with this excuse, that their pre- 

 iciibed course cannot have aroused any interest in Biology, 

 I viucationally, the syllabus of the Conjoint Board is a sin. 



L. C. M. 



Afterglows in Spain, 



HAVE read Mr. Backhouse's note in Nature (vol. xlvii. p. 

 5^21 on the afterglows as seen by him in Spain during February 

 last, and the doubts he expresses on the question whether this 

 phenomenon has always occurred when the sun has been near the 

 horizon. I have observed for many years the setting of the 

 lun in Cadiz on the sea horizon with the purest sky, and never 

 remarked the pink tint, but always the rosy tint in the west 

 and the purple, or Cegensghein, in the east. After the Kraka- 

 'tao eruption, in the clear sky of Madrid, the pink colour of the 

 'segment was always more or less visible ; and it has been more 

 marked in these later afterglows. The phenomenon is of the 

 same character as that of 1883, but much less brilliant. The 

 ipex of the segment rises frequently to 40°. 



1 have also many times observed the green ray (rayon vert) in 



vf^y different conditions of the atmosphere, but nearly always 



calm air ; this is not precisely a ray, but a flash of green 



that has a very perceptible duration of some tenths of a 



nd. Augusto Arcimis. 



'rvdrid, April 24. 



Soot-figures on Ceilings. 



I The phenomenon noted by Mr, Poulton in Nature 

 I (vol. xlvii. p. 608) is a matter of very common observation ; 

 I except in the detail of the nail-heads it has been often noticed. 

 ; The explanation is, I fancy, simpler than that suggested by Prof 

 ; Lodge. It is probably a simple case o{ sifting of air, as it passes 

 ■ by upward diffusion through the porous plaster, where its passage 

 I is not barred by contact of the plaster with the wood on the 

 ( upper side. The plaster acts as the plaster of Paris plug does in 



the classical researches of Graham on the diffusion of gases, and 

 ) as the plug of cotton-wool does in the common process of steri- 

 ; Using air in biological work. That warm air does stream up 



ilirr.ugh a plaster-ceiling in this way is a matter of experience to 



regards the origin of new species, the author, like Prof. Weismann, 

 «u. luutes the greatest importance to sexual reproduction, and especially to 

 cross ferlilisatton " (see ante, p. 606). 



NO. 1228, VOL. 48] 



every householder, when in the winter a bedroom over a sitting- 

 room in which a fire is kept burning all day and a lamp or gas- 

 flames for some hours in the evening, is always found to be drier 

 and warmer than another room in the same house not so 

 situated. We can scarcely classify dry wood and iron together 

 as conductors of heat. A, IRVING. 



Wellington College, Berks, April 29. 



The soot-figures on ceilings described by Mr. Poulton remind 

 me of the appearance of very similar figures brought out by hoar- 

 frost. The first time I noticed this effect was on the surface of 

 a smoothly-boarded gate, where the parts behind which the 

 bars of the framing ran were marked out by a much thicker 

 coating of hoar-frost than the rest. Subsequently I noticed the 

 same effect on a wooden pier where the planking was crossed by 

 broad belts of white, exactly outlining the timbers to which the 

 boards were nailed. On another occasion thick hoar-frost had 

 formed on the roof of the after-cabin of the steam yacht Medusa, 

 composed of a close pile of fine needles of ice about one-eighth 

 of an inch high, inclined at various angles. At first the places 

 where the thin teak boards were nailed to the cross-beams were 

 covered only a little more thickly than the rest, but as the warmth 

 of the day increased the ice spicules disappeared — evaporated 

 rather than melted — from the unsupported parts, but remained 

 in a broad band outlining each beam except above the nail- 

 heads, over each of which a small clear space had melted. 



At the time I satisfied myself that the phenomena were due 

 to peculiarities of melting rather than of deposition. Supposing 

 the whole surface to have been coated uniformly, the thicker 

 parts would take longer to heat up by the sun, and so tend to 

 prolong the life of the ice spicules resting on them. If this were 

 so, conversely the thickened parts of the structure, cooling more 

 slowly, should have received a lighter coating to begin with, but 

 this I was never fortunate enough to observe. Is the similarity 

 to the soot-figures accidental ? Hugh Robert Mill. 



I, Savile-row, April 28, 



As this subject has been under discussion lately in Nature, 

 it seems worth while recording a striking instance which 

 must be well known to many who have been in the large 

 mess room of the Royal Engineers at Chatham. This room 

 has a lofty, highly ornamented ceiling, which was for many 

 years bordered with a deep cornice with a plain moulding 

 either in plaster or papier machu, mostly stuck on one simple tem- 

 plate, and coloured either white or some very pale tint. The room 

 was lit by three sunlights in the roof, containing about i 90 gas 

 jets. In the course of time the whole of the white moulded cornice 

 became grey with soot-deposit markedat intervals with tight bars, 

 which were apparently the outline of the wooden ribs carrying 

 the mouldings. This pattern was fairly conspicuous, and was 

 often a subject of discussion at mess (1885 to 1890). Dr. A. 

 Lodge's explanation of the cause seems to be the true explana- 

 tion. Allan Cunningham. 



Kensington, April 28. 



The mapping out of the heads of nails driven into the joists 

 of the ceiling at Felixstowe seems to be inexplicable by the 

 theory of filtration, although this may very probably account 

 for the more common cases of a deposit between but not upon 

 the joists of a ceiling. I am endeavouring to get a photograph 

 of the best part of the Felixstowe ceiling. Dr. Mill's observa- 

 tion seems to be due, as he suggests, to a different process. 



E. B. Poulton. 



THE APPRECIATION OF SCIENCE BY 

 GERMAN MANUFACTURERS. 



"D ECENTLY,when giving evidence before the Gresham 

 ■•■^ University Commission, I had occasion to speak of 

 the attention devoted- in German chemical laboratories to 

 higher studies, and when asked what were the results of 

 this instruction I drew attention to an article published a 

 short time before in that inost enterprising of chemical peri- 

 odicals, the Cheiniker-Zeitung, edited by Dr. Krause. 

 In this article a description is given of the research labora- 

 tory provided to accommodate six- and twenty skilled 

 clieiiiists, attached to the works of the Farbenfabriken, 



