AND THE DISEASES OF PLANTS. 299 



ly executed, constant attention must be paid to watch and 

 remedy any accidental defect ; whilst the laws of Nature 

 are of so perfect a description that they are stored with 

 those remedies which the mechanist is obliged to supply. 



Mrs. B. The loss of bark is so serious an injury as 

 often to prove fatal to plants. If the evil prevail entirely 

 around the stem, so as to effect a complete solution of 

 continuity, the cambium can no longer descend, and the 

 plant must inevitably perish. 



Caroline. But do you forget, Mrs. B., that in cutting 

 a ring in the bark, to improve the fruit, you perform the 

 very operation you say is so dangerous ? 



Mrs. B. The ring, you must recollect, is so narrow, 

 that the swelling of the upper edge, from the accumula- 

 tion of sap, soon produces a re-union of the several parts: 

 but I was alluding to the destruction of the bark to so 

 great an extent as to preclude all chance of such a rem- 

 edy. If the bark be only rent on one side of the stem or 

 branch, it may be considered as a partial infirmity, of 

 which the plant may recover. For this purpose, the dis- 

 eased part should be carefully cut away, and the wound 

 be covered with an ointment. Let us suppose the rent 

 to be of a long oval form, as is generally the case ; the 

 cambium, when it reaches this spot, meeting with ob- 

 struction, will accumulate, and produce a swelling on 

 the upper edge of the wounded part : this will gradually 

 descend on each edge of the severed bark, till it meets 

 at the bottom, and the swelling will increase, till the two 

 sides unite, when the wound will be healed. 



Emily. I have often observed the swelling of the bark 

 where a branch has been lopped ; but it remains a protu- 

 berant ring around the wound, and does not close, so 

 that the central part of the wood remains exposed. 



Mrs. B. In this instance, not only no ointment has 

 been used to shelter the part affected, but the wound be- 

 ing of a circular form, it is more difficult for the edges 

 of the bark to meet. The young wood, however, which 

 it is the most essential to shelter, is covered by the swol- 



1612. What comparison does Caroline make between the laws of na- 

 ture and human mechanism! 1613. What does Mrs. B. say of the 

 loss of bark! 1614. Caroline thinks Mrs. B. has fallen into an incon- 

 sistency, as to the making a ring in the bark How is this explained! 

 1615. If the rent be made in a long oval form what will be the result! 



