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JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



asserts that the ultra-violet rays favour floral development.^ Others 

 allege the light intensity alone as the cause favouring the production of 

 brilliantly coloured flowers. Certainly the fact that plants which are 

 forced into flower by artificial means at a time of the year when the light 

 is less intense than it would be at their normal flowering season, pro- 

 duce relatively less brilliantly coloured flowers, seems to lend a certain 

 support to the view that the intensity of floral colouring depends on the 

 brilliancy of illumination. It is also suggested that the vivid colouring 

 of the flowers of alpine plants is due to a special adaptation for the 

 purpose of attracting insects, the vegetative period at high altitudes 

 being short, and the necessity for an early fertilization correspondingly 

 urgent. It would seem, however, not to be possible to assign this as 

 the cause for the phenomenon under discussion without, at the same 

 time, implying the existence of a selective process in favour of the 

 plants producing the more brilliantly coloured flowers. If the greater 

 intensity of floral colouring of alpine plants is due to a selective process, 

 it is difficult to understand that it should not have become hereditary, 

 yet the modification in the intensity of colour which the flowers, pro- 

 duced by specimens transplanted from the Alps to lowland gardens, 

 undoubtedly undergo, certainly seems to militate against this being the 

 case, while the increase in intensity of floral colouring which lowland 

 plants acquire when transplanted to high altitudes, still further seems 

 to negative the theory that brilliancy of floral colouring in alpines is due 

 to a selective process. The conflicting theories of botanists may well 

 confuse the layman, but we may still look forward with interest to the 

 time when further research and experiment shall have brought us a 

 stage nearer the elucidation of the fascinating but difficult problem.! 



Viewing as a whole the conditions of the alpine climate and sur- 

 roundings, and their wide divergence in almost every respect from those 

 obtaining in the moister atmosphere, and under the dull skies of our 

 own sea-girt island, we may well marvel at the success which attends 

 our efforts in cultivating alpines in our own gardens. True it is that 

 there are some species which not even the efl'orts of our ablest culti- 

 vators can bring to the full glory of their development. Androsace 

 glacialis, Eritrichium nanum, and some of the Gentians which conrie 

 from close to the everlasting snows, are among the most unresponsive 

 to treatment. The wonder is that the recalcitrants are so few. We 

 can, by means of green-houses and damping down, produce a very fair 

 imitation of a moist, tropical climate, but the reproduction of the alpine 



* Sachs, " Ueber die Wirkung der ultra-violett'en Strahlen auf die 

 Bliithenbildung. " Arheiten aus dem botanischen Institvt zu Wurzhurg, Bd. Ill, 

 1884 [Ges. Ahhandl. 1, p. 354). 



t {a) Schimper, oj). cit. p. 706, et. seq. ; (6) Dodel-Port, A. " Farben, Pracht 

 und Grosse der Alpen Blumen," Kosmos, Bd. 1, 1879; (c) Heekel, Ed., " Sur 

 I'intensite du coloris et les dimensions considerables des fleurs aux hautee alti- 

 tudes," Bulletin de la Societe hotavigue de France, Tome xxx., 1883; 

 (d) Keller, E., "Die Bliithen Alpiner Pfianzen, ihre Grosse nnd Farbenintensitat " 

 offentliche Vorlage, gehalten in der Schweiz, Bd. ix., 1887 ; (e) Sargnon, " Causes 

 du vif coloris que presentent les fleurs des hautes sommites alpines." Annales 

 de la Sociite botanique de Lyon, Tome vii., 1879. 



