194 CULTIVATION. 



tings of hardy plants, that the point most favour- 

 able to the formation and production of roots is 

 but at a little distance below the surface ; and 

 that humid darkness within the influence of air 

 excites the protrusion of roots more readily than 

 at depths beyond the influence of that element. 

 Small pots, therefore, to which air has free access 

 on all sides, are found to forward the plants 

 they contain much better than large pots, which, 

 containing a mass impervious to air, the centre of 

 which is occupied by the infant plant, are found 

 to retard rather than advance their growth. That 

 plants so placed require frequent shifting, is true ; 

 but this is all in their favour, if quick growth be 

 desirable. 



After this period of their nursing, they then 

 take their places in the hot-house, either plunged 

 in the bark-bed, or set on the shelves over tbe 

 flues, or on the kirb of the pit. 



Hot-house plants are also propagated by cut- 

 tings. Much judgment is necessary in selecting 

 such shoots as are proper. They should be shoots 

 or parts of shoots of the present year ; either of 



