56o 



NA TURE 



[April 17, 1902 



intervals of the twigs and smaller branches of these trees, and 

 their content in starch was carefully tested and observed. The 

 general result was that the ivy is a decided starch-tree, inasmuch 

 as at no time during the winter was its wood found free of 

 starch or anyway nearly so. No doubt, as compared with 

 summer, there was a great diminution of this substance, many 

 of the medullary ray cells being completely empty of granules, 

 and moreover, e.g. on January i8, only about one-quarter of 

 these cells were stored with starch, and even this gave a reddish- 

 brown tinge to iodine, as if ainylodextrin was intermixed 

 therewith. As regards the holly, there could be no question 

 that the amylaceous reservoirs of its wood had sufiered a still 

 more serious depletion. Nevertheless, they were never found 

 completely void, a more or less considerable accumulation of 

 starch granules being readily distinguishable along some portion 

 of the medullary rays ; the pilh, too, was never empty (that of 

 the ivy was found invariably depleted). It may be added that 

 in both cases starch was completely absent from the bark during 

 the winter months. 



The overthrow by the boisterous gales of the departing year 

 of a crab-apple that was perched aslant on a sharp ridge of rock 

 afforded an opportunity for observation of the root appanage of 

 this tree. The wood of the root contained a considerable 

 amount of starch, but none was found in its bark. The alco- 

 holic and aqueous extracts of the latter proved very rich in 

 phloridzin, the reactions thereof being yielded with eminent 

 distinctness and beauty, and the phloretin prepared from it 

 indicated by its behaviour in alkaline solution with nitro- 

 prusside of sodium that it was a fatty aromatic ketone. Phloro- 

 glucin was detected in the wood, but none in the bark. 



Whilst exercising on the hills on January 19, numerous faded 

 and embrowned brackens were seen which a week or so 

 previously had been overlaid with a thick mantle of snow. The 

 fronds of one of these were incinerated, and the crude ash was 

 found to contain no less than 43'6 per cent, of silica, also I3'2 

 CaO and o'S phosphorus (or I "8 PoO.,). This enormous 

 amount of silica is all the more remarkable, inasmuch as in 

 August the ash of the fronds contains only about 9 per cent, of 

 this constituent and that of the stem about 7 per cent. — the 

 difference is doubtless to be attributed to the very considerable 

 diminution of the soluble salts, and not of the lime, during the 

 course of autumn. In this case, as in that of all calcifugous 

 species, a strong proportion of lime in the young and vigorous 

 frond would offer a serious obstacle to the presence of a con- 

 siderable quantity of potass. Thus, on June 3 the amount of 

 potass and soda in the ash is somewhere about 32 per cent., in 

 August 27 per cent., and in late autumn about 2 or 3 per cent. 

 The lime, on the other hand, fluctuates from about 6 to about 

 13 per cent, only, and thus while in a great many leaves the 

 autumnal deficit is, so to speak, covered by lime, here in the 

 case of the bracken it is refunded by a lavish plethora of silica. 

 The general inference is that the frond, having been utilised as 

 a support for the reproductive parts (sporangia), the strain 

 thereby involved leads to a very advanced condition of decay, 

 whence a tremendous drainage of silica towards the organ. 

 Perhaps it is this very faculty of remaining decayed without 

 disfigurement, encased in silica, that is one of the causes why 

 abundant remains of ferns are found in the fossil state. 



Patterdale, Westmorland. P. (j. Kekg.vn. 



The Species Problem in Corals. 



May I direct the attention of your readers to an exhaustive 

 article, dealing specially with "species " among the reef-corals, 

 by Prof. Dciderlein in the current number of the Zcitschrift fiir 

 Morpholoi^ie and Authropologie? It is somewhat hard to find 

 myself there blamed for continuing to use the word "species" 

 in relation to a group in which it is totally inapplicable, for I 

 laid the whole subject before the Linnean Society a year ago. 

 I stated the difficulty and suggested a provisional alternative 

 method of designating specimens. I carefully explained that I 

 was proposing a method of work in order that we might discover 

 the true species by gradual arrangement of the variations. In 

 the autumn of the same year I made a brief statement at the 

 International Congress of Zoologists in Berlin, but the report 

 has not yet appeared ; and again, later in the year, I read a 

 paper before the Cambridge Philosophical Society. This has 

 appeared in the last number of the Proceedings of that Society 

 under the title "On the Unit of Classification for Systematic 

 Biology." 



NO. 1694, VOL. 65] 



It will he noticed that while Prof. Ddderlein discusses the 

 general problem very fully, he makes no practical suggestion as 

 to how to designate the different forms for reference. I, 

 struggling with nearly a thousand foolscap pages (dealing with 

 three genera) for the " Catalogue " of the (jreat National Col- 

 lection of Corals at South Kensington, was compelled to 

 invent some way of labelling them. But before finally adopting 

 it, I sought the advice of many of the leading zoologists and 

 botanists within reach. Henry M. Bernard. 



Clapham, S.W., March 21. 



Sun Pillars. 



On January 19, 1901, during zero weather at Winnipeg, 

 Manitoba, the fine icy particles which floated over the city as a 

 cloud at II a.m. gave a halo round the sun with two mock suns 

 to the right or left at the same altitude as the sun, and above the 

 halo an inverted arc of about 120° showing prismatic colours. 

 There was a good deal of wind at the time. 



At night the wind dropped and the air became very still. The 

 haze of icy particles descended, and in the middle of the night 

 its illumination by the strong 

 arc lamps of the city gave a 

 column of light; comparable 

 to a sun pillar, extending 

 above each lamp to a height 

 estimated at 300 feet. A 

 striking feature of the phe- 

 nomenon was the perspective 

 effect, the columns diminish- 

 ing in apparent height in such 

 precise proportion to the in- 

 creasing distances of the 

 street lamps that it was 

 evident the upper surface of 

 the cloud of particles was 

 truly horizontal. At this time the 

 vertical columns of light were 

 also visible below the lamps 

 and extended to within a few 

 feet of the ground. A few 

 hours' later, viz. at 4 a.m. 

 January 20, the lower ends of 

 the columns were more than 

 60 feet from the ground, and 

 therefore far above the lamps. 



They extended to a height of about 300 feet, as judged by 

 the distance of the nearest lamp and my elevation above the 

 ground, which was about 60 feet. A narrow rift extended 

 horizontally through the cloud, breaking each column of light 

 into two parts. The figure is re-drawn from a rough sketch 

 made at this time of the columns above three, only, of the 

 numerous arc lamps. 



The slight haze of minute icy particles which is common in 

 zero weather is, I believe, called fotidretle in Eastern Canada 

 Vaugiian Cornish. 



Swarm of Velella. 



On a former occasion while sailing in the Mediterranean I 

 have noticed the abundance of this beautiful Hydro medusa, 

 usually known as the " Portuguese Man-of-War," sometimes 

 distributed over the surface of the sea, but never in numbers 

 such as have been stranded along the northern shores during 

 the past few days. 



When taking my usual morning bathe at Mentone on April 5, 

 I plunged into a living mass of these Siphonophora, which 

 extended many yards from the shore. It was about the sarne 

 on the 6th, when I gathered a number and preserved them in 

 formol (5 per cent, from the 40 per cent, solution). Since then 

 the shore has been literally strewn with them, a very disagree- 

 able odour being emitted. At Bordighera yesterday and here 

 to-day, nearly fifty miles from Mentone, their dried remains 

 strew the shore and appear to be well preserved, though, of 

 course, minus their beautiful colour. We have had no strong 

 south winds, and I cannot see how to account for so remarkable 

 a shoal. Isaac C. Thomtson. 



.Massio, April 9. 



