528 THE PARKS AND GARDENS OF PARIS. [Chap. XXXI. 



nurserymen could scarcely confer a greater benefit on all who care 

 for flowers in the house, than preparing Lilac-bushes for flowering 

 in windows in town and country. It would prolong so delightfully 

 the season of this too short-lived flower. I look forward to seeing 

 them plentiful in London houses, where the absence of strong light 

 would tend to subdue the reddish pigment and give us the pale 

 but sweet flowers. The subject is a very interesting one, so both 

 sides of the question are here given ; but I am glad to find that 

 experiments by M. Lavallee and others in France place the 

 matter beyond all doubt as to the facility of their production in 

 the light. 



I extract the following particulars respecting the production of 

 the white variety of the coloured Lilac from an interesting article 

 by M. A. Lavallee, Secretary-General of the Societe Centrale 

 d'Horticulture de France, published in a recent number of the 

 Society's journal: — In December, 1876, M. Lavallee laid before 

 the Society several branches of the Eed Marly Lilac with perfectly 

 white flowers, and at several subsequent meetings he exhibited 

 similar specimens, all of them produced upon a system differing 

 from that generally adopted. The most usual method of obtaining 

 the artificial white Lilac is to grow the plants in a greenhouse 

 from which every ray of light has been carefully excluded, but M. 

 Lavallee has proved, by repeated experiments, that absolute 

 darkness is not essential for producing the white flowers. The 

 effect of darkness, perfect or partial, on the plants is due to the 

 well-known principle of vegetable physiology, according to which 

 the colouring-matter of leaves known to chemists as chlorophyl — 

 itself, by the way, being a mixture of variously-coloured con- 

 stituents—can only be perfectly developed under the influence of 

 light. This principle has long received valuable applications in 

 the blanching of Seakale, Celery, Endive, Asparagus, etc., but it 

 is only lately that it has been applied to the bleaching of flowers, 

 and, as far as I know, in the case of the Lilac only. M. Lavallee 

 goes on to point out the needlessness of growing the plants in 

 perfect darkness, and observes that the mistake which horti- 

 culturists have made has arisen from the fact of their having 

 confounded two distinct notions, the one being that leaves grown 

 in darkness are pale or colourless — the other, the absence of colour 

 in flowers in which the colourless principle has never been 



