262 PEINCIPLES OF GARDENING. [CH. VIII, 



mediately or remotely, to induce or exasperate the 

 attacks of the ambuiy. 



I am about in the first place to consider the 

 disease exclusively as aifecting the cabbage, and 

 secondly, as it operates upon the turnip, though 

 other species of brassica, the hollyhock, &c., are sub- 

 ject to its attacks. Its progress has invariably ap- 

 peared to me as follows : 



Cabbage-plants are frequently infected with ambury 

 in the seed-bed, and this incipient infection appears 

 in the form of a gall or wart upon the stem, im- 

 mediately in the vicinity of the root's. If this wart 

 is opened, it will be found to contain a small white 

 maggot, the lan^a of a little insect called the weevil. 

 If the gall and its tenant being removed, the plant is 

 placed again in the earth, where it is to remain, unless 

 it is again attacked, the wound usually heals, and 

 the growth is but httle retarded. On the other hand, 

 if the gall is left undisturbed, the maggot continues 

 to feed upon the alburnum or young woody part of 

 the stem, until the period arrives for its passing into 

 the other insect form, previously to which it gnaws 

 its way out through the exterior bark. The disease 

 is now almost beyond the power of remedies. The 

 gall, increased in size, encircles the whole stem; 

 the alburnum being so extensively destroyed, pre- 

 vents the sap ascending ; consequently, in dry wea- 

 ther, sufficient moisture is not supplied from the roots 



