530 THE PARKS AND GARDENS OF PARIS. [Ohap. XXXI. 



specimens of the Charles X. yariety were shown by M. Lavall^e, 

 both of which were grown in the light, but under different 

 conditions of temperature. The first one, which had pale lilac- 

 flowers, was placed in a house heated to a temperature of 68^ Fahr. 

 on December 23, 1876, to force its growth. At the end of four or 

 five days the flower-buds began to make their appearance, and it 

 was transferred to a cool house, the mean temperature of which 

 was 40° Fahr. The flowers began to open about January 10, and 

 were of a pale lilac. The shade of colour having been carefully 

 noted, M. Lavallee replaced the plant in the forcing-house, which 

 was now at a temperature of 70^ Fahr., in order to see if the heat 

 would have the effect of destroying the small amount of colouring- 

 matter already formed ; but not the slightest change took place, 

 the flowers preserving exactly the same tint. The second specimen 

 had perfectly- white flowers, and was put in a well-lighted forcing-' 

 house on December 30, where it remained until it was exhibited 

 to the Society. Two specimens of the Marly Lilac, with equally 

 white flowers, were also shown. They were grown in a well-lighted 

 forcing-house at a temperature of 72° Fahr. To vary the experi-. 

 ment, several plants which had produced pale lilac blossoms in a cool 

 house were transferred to a perfectly-dark forcing house, but 

 without the slightest change taking place in their colour. 



From these experiments we may draw the conclusions — that a 

 prolonged heat of from 68° to 72° Fahr. prevents the formation of 

 the colouring-matter in the petals of the Lilac, but that when once 

 it has been formed, this temperature is incapable of destroying it, 

 and that a temperature of 40° Fahr. has no influence on the 

 colouring-matter of the flowers of these plants. M. Lavallee 

 therefore supposes that it is on account of the rapidity of their 

 growth in the forcing-houses that these Lilacs produce colourless 

 flowers, and that darkness has nothing whatever to do with the 

 phenomenon ; also that when the Lilac is forced into blossom in 

 fourteen, fifteen, or even twenty days, the colouring-principle has 

 not sufficient time to develop itself. Whenever, therefore, we 

 wish to obtain Lilac with white flowers, all we have to do is to 

 place the plants in a forcing-house, the temperature of which is 

 kept at 68° Fahr,, without seeking the aid of darkness. This 

 method of producing artificial white Lilac is extensively practised 

 by the country people in the neighbourhood of Antwerp. They 



