302 JOUKNAL OF THE EOYAL HOKTICULTUKAL SOCIETY. 



This method now seems likely to be supplanted by that of hot-water 

 forcing. In 1906 M. Ferd. Molisch, of Brunn, tried plunging lilacs in 

 November into water at a temperature of 30°-36° 0., maintained at con- 

 stant temperature for ten to fifteen hours, after which they were forced in 

 the usual way. In Russia the same method was applied to lilies of the 

 valley. The crowns to be forced were soaked for twelve or sixteen hours 

 in water at 35° C. ; they were then forced at 30°-32-5° 0., and flowered 

 several days before the control plants. 



Seeing these practical effects Professor Hans Molisch made a scien- 

 tific study of the method, which is summarized as follows : 



1. If shoots or rooted shrubs are plunged into water at 30° or 40° C. 

 during their resting period (only the aerial part of rooted plants being 

 plunged), and soaked for several hours, and subsequently grown 

 on in moderate heat, the resting time will, in many cases, be 

 shortened, and the buds will develop more quickly, The process succeeds 

 well with the following : Corylus Avellana, Syringa vulgaris, Forsythia 

 suspensa, Cornus alba, Bibes Grossularia, Larix decidua, Bhamnus 

 Frangula, Aesculus Hippocastanum, Salix, Fraxinus excelsior, &c. 

 Besides the kind of plant and season of the year, success depends on the 

 following factors : — 



a. Length of bath. Six to twelve hours is usually enough. It is 



well not to exceed twelve hours, because oxidation is very 

 active at this high temperature, and as the 0 content of water 

 is very limited, the respiration of the plants is hampered, and 

 the buds are damaged or destroyed. 



b. The temperature must vary for different plants, and must be 



found by experiment. Corylus, Forsythia, Bibes, Syringa are 

 started by a bath of 30° C, while Cornus, Bhamnus, and 

 Betula alba require 35° to 40° C. 



c. The action of the bath depends upon the stage of rest that the 



plants are in. In some it takes effect directly the leaves have 

 fallen, in others much later on. If boughs of ash and horse- 

 chestnut are soaked early in the autumn, they will not force ; 

 soaked in December and January, they come on well. 



2. The action is purely local. This can be seen by plunging only half 

 the shrub, when the result is unmistakable. A lilac soaked on one side 

 only in November, and then forced, will soon be covered with bloom on 

 the one side, while the other retains its winter appearance. 



3. The effect of the hot bath persists even when the plants thus 

 treated are put out in the ground for the rest of the autumn or winter. 

 Directly they are taken up and forced, they react like the plants forced 

 directly after the bath. 



4. A prolonged bath of damp air at high temperature has the same 

 effect on many plants as a warm bath at even temperature. In some cases 

 it is even more successful, showing it to be the great heat that in the first 

 instance sets up the changes. Up to the date of this article, however, the 

 moist air bath had only been tried at the end of the autumn, when the 

 resting state is less profound than earlier in the season — so that further 

 experiments must be made. It also remains to discover how the heat- 



