ArnrsT. 1901.] 



KNOWLEDGE 



109 



J^^^IUSTRATED MAGAZINE << 



iciEN€E,ilTERATpE k^M 



Founded by RICHARD A. PROCTOR. 



YoL.xxiT.] LONDON : AUGUST, 1901. [No. 190. 



CONTENTS. 



^ PAOK 



Flowering Plants, as Illustrated by British Wild- 

 Flowers.— IV. Flowers and Fruits. By K. Lloyu 

 Prakgek, B A. rUIttstrated) .' 169 



How Arctic Animals turn White. By K. Ltdekkeii 172 



The White Nile — From Khartoum to Kawa. — III. The 

 Country and the People. By Haert F. Withebby, 

 F.Z.S., M.B.o.r. (Illustrated^ 174 



The Brightness of Starlight. By J. E. Gore, f.r.a.s. ... 177 



Constellation Studies. — VIII. The Archer and the 

 WaterBearer. By E. 'Waiter Maunder, f.r.a.b. 

 ( llhtalrateil/ ... ... 178 



Photographs of the Nebulae ¥ V. 32 Orionis, H IV. 2 

 Monocerctis. y IV. 28 Corvi, and « I. 139 (M. 61) 

 Virginis. By Isaac Roberts, d.sc. f.r.s. (Platf) 1>(0 



The Second Series of Lines in the Spectrum of 



Hydrogen. ^\ Ep-n-ARn C. PicKERiyo isl 



Letter : 



Lr.vAE Atmosphere and 0( bans. By J. O'May ... 1S2 

 British Ornithological Notes. Conducted by Harht F. 



WiTHEEBT, F.Z.S., M.B.o.r " 1H2 



Notices of Books 183 



Books Received 185 



Notes ISo 



Men and Microbes. By E. STBXHorsE, a.r c.s., B.st. ... 187 



Microscopy. Conducted by 51. T. Cross ... ISH 



Notes on Comets and Meteors. Bv W. F. Denning, 



F.K.A.S " 190 



The Face of the Sky for August. By A. Fowler, f.e.a.s. 191 



Chess Column. By C. D.Locock, b.a 190 



FLOWERING PLANTS, 



AS ILLUSTRATED BY BRITISH WILD-FLOWERS 

 By K. Lloyd Praeger, b.a. 



IV.— FLOWERS AND FRUITS. 



Some of the leading characteristics of those all-imjiortaiit 

 parts of plants which we call flowers wei'e touched on 

 in my last article, and the uses and more striking 

 variations in shape and colour of the individual blossom 

 were briefly dealt with. From the individual flower we 

 may pass on to the consideration of infloi-escences, or 

 groups of flowers considered as a whole. Most of the 

 wind-fertilized plants have their flowers arranged in 

 more or less elaborate inflorescences — the beautiful com- 

 pound panicles of many grasses furnish examples, and 

 the dense flower-spikes of the Reed-mace and the sedges. 

 In these cases, as already pointed out, the most 

 advantageous position for the flowers to occupy is the 

 apex of the stem, where they will receive the greatest 

 amount of air and light, hence the minute flowers of 



plants such as the above-named are crowded together, 

 often in enormous numbers, at the top of the upright 

 stems. In insert-fertilized flowers, where conspicuous- 

 11CSS is a desideratum, development has proceeded in two 

 directions, and showincss may be ihio either to the great 

 eiil.ugenieiit and coloration of parts of tlie individual 

 flower, or to the grouping in a dense inflorescence of 

 immeroiis smaller flowers — and, of course, all kinds of 

 combinations of these conditions occur. Tn most of the 

 plants in which the fonner extreme prevails, the flowers 

 are solitai-y ; the single blossom is sutliciently con- 

 spicuous to attract the attention of insects. 



Tn the second photograph in my last article, the 

 contrast between these two methods of " advertising " 

 is clearly shown. Many instructive examples of the 

 giouping of blossoms are to be found among our familiar 

 wild flowers. Our commonest Orchids, such as belong to 

 the genera Orchh, Hahennrin, and Lixterii, have their 

 blossoms arranged in a dense ><pike — a close-ranked 

 Ijvramidal or cylindrical mass of flowers. But no one 

 blossom covers or obscures another — a fact the more 

 noteworthy when wo recollect that each, as it expands, 

 twists itself upside down. In the Teasel, each of the 

 little lilac flowers which form the dense head is sub- 

 tended by a stifl' quill-like bract, which, projecting far 

 beyond the blos.som, forms an efl'ective protection against 

 grazing animals, while providing a convenient platform 

 on which insects may alight. In the large order of 

 V inhelUfera, to which the Carrot, Hog-weed, and Parsley 

 belong, a singularly conspicuous flower-mass is produced 

 by means of an elaborate system of branching. The 

 flowering stem divides at one point into a number of 

 short radiating branches, of which the outer are the 

 longer, so that the apices of a.ll lie in a plane or slightly 

 convex surface. If a flower were borne at each apex, a 

 ■umph umbel would result ; but in most of our com- 

 moner representatives of the order, each branch again 

 divides into a similar series of branchlets, each of which 

 bears a blossom. A large and conspicuous, flat circular 

 expanse of flowers is the result. Similar effects are 

 produced in some other familiar plants by a less formal 

 mode of branching — the Elder, for instance, furnishes a 

 case in point. In some of the common UmJicUifercp. an 

 interesting feature may be noted. If the inflorescence 

 of the well-known Hog-weed be examined, it will be 

 observed that in those flowers of each umbellule or 

 secondary umbel which are outermost, and especially in 

 those which form the margin of the whole umbel, the 

 ))ctals on the outer side are considerably larger than 

 those on the inner side. The petals of the inner flowei-s, 

 and the inner petals of the outer flowers, could not 

 increase in size without interfering with the neighbour- 

 ing flowers ; but where there is room for expansion, the 

 plant has not lost the opportunity of rendering its 

 blossoms more conspicuous. A similar feature may be 

 noted in plants belonging to other orders — in the Field 

 Scabious, for instance, where the outer flowers of the 

 close head possess much enlarged corollas, which are 

 cjuit« unequal owing to the greater grovvtii of the free 

 side. In certain other familiar plants, this idea has been 

 adopted to a much gieat.er extent. Examine the 

 inflorescence of the common Gueider-Rose, Vihurniini 

 Opulwt. The greater number of the flowers of each large 

 ci/me have small corollas of a greenish white colour. 

 But the marginal flowers have large white corollas, to 

 produce which the essential parts of the flower — 

 stamens and pistil — have been sacrificed. The flowers 

 ! consist simply of a great corolla, and their object is to 



