324 



KNOWLEDGE & SCIENTIFIC NEWS. 



[Jam'ary, 1906. 



slrikinsj appearance of our Cowslip. These are pro- 

 duced in clu.sters of three, and would scarcely be notice- 

 able amongst the foliage were it not that each cluster of 

 blooms is surrounded by three conspicuous bracts. 

 These bracts aie exactly in the form of leaNcs, but are 

 coloured in a highly attractive tint of bright lilac. Pre- 

 sumably this strange dcvt'lopment is to attnict the 

 atlentio'n of insects, as a Bougainvillea in full bloom is 

 an object which would be conspicuous from a consider- 

 able distance. In much the same fashion Brazilian 

 Euphorbia (Poiritsc/Zia pulchcrnma) has been able _ to 

 call attention to its green flowers by surrounding 

 these with a circle of bracts coloured with the brightest 

 crimson. In each of the cases mentioned above it is 

 impossible for the student to determine definitely 

 whether the bracts mav be referred to :is k'aves or 

 p.tak. 



THE SUMMER SNOWFLAKE.— In this flower the leaf origin of the 

 petals and sepals Is easily discernible, each organ having a green spot. 



;\ more familiar plant than either of the showy 

 exotics referred tO' is the Salvia hrrnmium rubra, a 

 common garden species. This plant has seen fit to 

 resort to extraordinary means to advertise its small 

 labiate flowers. When the Salvia is in bloom the 

 terminal Icives of each flowering spike are coloured in 

 the brightest pink. That these are true leaves is verv 

 evident frcmi the fact that as one proceeds down the 

 stem it is possible to find leaves which are half green 

 and half pink, until one arrives finally at the whollv 

 green leaves. 



A further remarkable proof of ihr fan that the petals 

 and sepals of the flower ha\e their origin in the leaf is 

 to he seen in the case of such a species as the Christmas 

 Rose. This plant, as is well known, produces white 

 blossoms during the winter time. What one may call 

 the corolla of this flower is peculiarly tenacious in re- 

 taining its position on the stem, even after the essential 

 organs of the flower are p;ist their maturity. This 

 corolla is really made up of petal-like sepals', the real 

 petals being small processes scarcely distinguishable 

 from Ihe stamens of the flower. But the curious part 



about these white sepals is the fact that when the flower 

 is " over " they do not fade away as one might expect, 

 but gradually lose their whiteness and eventually be- 

 come green and leaf-like in appearance. Much the 

 same process goes on in the case of the Hydrangea and 

 its show v bracts. Of course, it is well known that the 

 attractive part of the Hydrangea heads of bloom are 

 merely showily coloured bracts surrounding inconspicu- 

 ous flowers. These bracts remain long after the real 

 flowers have faded, and gradually lose their colour, 

 finally becoming as green as the leaves of Ihe plant 

 itselfl 



Moreover, there are many species of plants in which 

 the coloured parts of the flowers gradually develop from 

 very green materi.al. This is seen in the case of some 

 of the (iuelder Roses {Viburnum). As a matter of fact, 

 in many species the undeveloped sepals and petals 

 practically perform the offices of leaves during the early 

 stages of their existence. 



Numerous instances might be cited in support of the 

 examples given above, but these would be little more 

 than a reiteration of similar facts. Regarding the 

 evolution of the sepals and petals of the flower from 

 the leaf the case is surely a proven one beyond all doubt. 

 (To be continued. ) 



Star MaLp. No. 7. 



Virgo, Corvus. Centavirus. 



The important features included in this map are the 

 first magnitude star Spica and the Southern Cross. The 

 objects of special interest are not numerous. 



27 Hydra- (X h. 20 m. — 18'^'). A planetary nebula. 

 Spectrum gaseous. 



7 Virginis (XII h. 37 m. — 0° 56'). A binary, distance 

 apart 5"74. 



a Virgims (Spiea) (XIII h. 20 m.— 10° 40'); i-2 magni- 

 tude. Shown, by the movement to and fro of the lines 

 of the spectrum, to be a binary with a small or feebly 

 luminous companion. 



w Cciitauri (XIII h. 21 m. — 46° 57). A fine star clus- 

 ter, visible as a hazy object to the naked eye. Contains 

 some 6000 stars, of which 125 are proved to be variables. 



The following are the Lecture Arrangements at the Royal 

 Institution, before Easter: — A Christmas Course of Six Illus- 

 trated Lectures, adapted to a Juvenile Auditory, by Professor 

 H. H. Turner, on "Astronomy." Professor E. H. Parker, 

 Three Lectures on Impressions of Travel in China and the 

 Ear East ; Professor William Stirling, Six Lectures on 

 Physiology Subject; Dr. J. E. Marr, Three Lectures on the 

 Influence of Geology on Scenery (the Tyndall Lectures) ; 

 Rev. Canon Beeching, Two Lectures on Shakespeare ; Mr. 

 Benjamin Kidd, Two Lectures on the Significance of the 

 Future in the Theory of Evolution ; Mr. H. B. Irving, Two 

 Lectures on the English Stage in the Eighteenth Century; 

 Mr. Francis Darwin, Three Lectures on the Physiology of 

 Plants; Professor B. Hopkinson, Three Lectures on Internal 

 Combustion Engines (with Experimet:tal Illustrations) ; Mr. 

 J. E. C. Bodley. Two Lectures on the Church in France ; Mr. 

 J. W. Gordon, Two Lectures on Advances in Microscopy; 

 Mr. M. H. Spielmann, Two Lectures on George F'rederick 

 Watts as a Portrait Painter; and Professor J. J.Thomson, 

 Six Lectures on the Corpuscular Theory of Matter. The 

 Friday Evening Meetings will commence on January ig, when 

 Professor J. J. Thomson will deliver a Discourse on Some 

 AppUcations of the Theory of Electric Discharge to Spec- 

 troscopy. Succeeding Discourses will probably be given by 

 Professor S. P. Thompson, Mr. H. F. Newall, Mr. W. C. D. 

 Whetham, Dr. K. Caton, Dr. Hutchison, Sir Andrew Noble, 

 Bart., Professor P. Zeemanr;, Mr. W. B. Hardy, and other 

 gentlemen. 



