THE TRP]ATMENT OF ROOTS 87 



up with a pointed stick this dense felted mass of rootlets and 

 tearing it away. Experience has proved the utility of this 

 practice if carried out moderately. If this felt-work of rootlets 

 is left intact, and the whole ball of roots is immersed, just as 

 it is, in a larger pot, the earth at the centre has first of all not 

 been renewed ; and secondly, a tremendously dense mass of 

 roots partially damaged (by the removal of the old pot) is 

 replaced in a new, moist soil, containing a large amount of 

 humus. This dense mass of roots requires a very large amount 

 of oxygen, which it could formerly obtain, being pressed against 

 the side of the pot ; but now the conditions have changed. 

 In the new soil, which is richer in decomposing organic matter, 

 and therefore requires for itself a larger amount of oxygen, a 

 number of the pores are blocked by water, which absorbs the 

 products of decomposition, especially the carbonic acid. It is 

 this water which surrounds the felted mass of roots. Conse- 

 quently the injured portions of the root system often begin to 

 decay. 



Secondly, the root-tips which remain pressed together retain, 

 in the first instance, the direction of their growth, and only 

 slowly bend towards the sides of the pot, whereas it is most 

 advantageous for them to push as soon as possible strong root- 

 tips towards the better aerated region on the inside of the 

 pot. It is therefore better to remove a portion of the old net- 

 work of roots, and so to open up a passage for the rapidly 

 growing new roots to the side of the pot. Especially in the 

 case of herbaceous plants will it be noticed that those with a 

 loosened ball will most rapidly re-establish themselves in the 

 new pot. 



With regard to the mixing of a mould for pot-plants, we 

 may adopt the general rule that it must be coarse, but not so 

 light as to cause any danger of drying up. This is especially 

 to be borne in mind in the case of plants grown in dwelling- 

 houses. 



(d.) The Treatment of Boots in Transplanting in the Open. 



In the case of short-lived herbaceous plants grown in the 

 open ground, the treatment of the roots is very simple. In 



