Principles of Gardening physiologically considered. 197 



ation being surrounded by high trees. We were informed that 

 the plan was successful. We left Bothwell Castle deeply im- 

 pressed with the grandeur of the scenery and the noble river, 

 and full of respect and esteem for the moral worth and profes- 

 sional skill of Mr. Turnbull. 



( To be continued. ) 



Art. II. The Principles of Gardening physiologically considered. 

 By G. Regel, Gardener in the Royal Botanic Garden at Berlin. 



(Translated from the Garten Zeitung.~) 



{Continued from p. 160.) 



I. On the Propagation op Plants — continued. 



2. MEANS OF ACCELERATING THE FORMATION OF ROOTS. 



It has been shown above that the formation of roots is inti- 

 mately connected with the assimilation of the nourishing matter ; 

 to hasten the rooting, therefore, we must apply some means of 

 forwarding the process of assimilation. 



This consists, as is the case with seeds, in a moderately warm 

 state of the ground: the time must also be chosen in which 

 the same process is going forward in the parent plant. Of 

 some plants particularly difficult to root, such as Scott/tf, Draco- 

 phyllum, Cosmelia, some species of .Erica, &c, it is necessary 

 to take as strong compact-growing cuttings as possible; and, as 

 soon as circumstances permit, the plants intended for propagating 

 should be planted out in an open bed in the house. Those plants 

 which can be propagated successfully late in the summer, such as 

 heaths, may be planted out quite in the open air in summer; from 

 which this advantage is to be expected, that, by their naturally 

 much stronger growth, much more nourishing matter will have 

 been deposited by the end of the season. 



For cuttings of all the difficult-rooting greenhouse plants, the 

 best heat for the ground is from 10° to 12° R. ; for those of 

 hothouse plants from 12° to 16°, which should be as regular as 

 possible. This, which is often neglected, is of great moment 

 to insure the success of the cuttings ; for, if they are kept at a 

 cooler temperature, the greater part of them form a callosity, 

 but, for want of the necessary heat to assimilate the deposited 

 nourishing matter, no roots are formed. The callosity con- 

 tinues in many species to grow (such as Quercus, Hakea, and 

 I^rotea), and often becomes of so considerable a size, that it not 

 only covers the face of the cut with a thick layer, but also pene- 

 trates between the wood and the bark. When this is the case, 



o 3 



