710 APPENDIX. 



1032, in p. 486. The principal point to be attended to, in order to keep the old 

 branches furnished with young shoots, is, occasionally ringing or notching them ; 

 and keeping the whole of the young shoots which the shoots so treated throw 

 out stopped at every third or fourth joint throughout the summer. H. C. O. 



1115, in p. 525. In Russia and the North of Germany mushrooms are fre- 

 quently grown in shelves in a cowhouse or stable, in which also other articles are 

 forced. (G. M. vol. vii. p. 653). 



1153, in p. 544. Canker in fruit trees, like the cancer in the human body, appears 

 to be owing to a diseased state of the sap or blood, producing morbid concretions, 

 of an inferior degree of organisation to the tissue by which they are surrounded, 

 which they live on, and destroy, like parasites, till vitality is arrested. Plants 

 being a congeries of separate distinct beings, which have each an independent exist- 

 ence of themselves, may be more easily renovated by amputation and removal of 

 the exciting causes ; but in these, also, the sap is affected, as it breaks out in 

 ulcerous morbid sores often, when to all appearance removed. Willdenow 

 characterises it as produced by an acrid corroding gum, caused by the acid fer- 

 mentation of excess of sap from low-lying damp gardens. Others have thought it 

 to be of a fungoid nature, propagating itself as above stated, and living on the 

 healthy tissue, which it disorders and destroys. It is evidently aggravated, if 

 not produced, by a bad climate, and removed by a good one ; as trees that are very 

 apt to canker in the open ground are generally free of it on good walls. It is also 

 produced by a too rich damp state of the soil, as it is often removed by remedying 

 this, and laying the ground dry and sweet about the roots. It is also constitutional ; 

 as some sorts are liable to be hurt, while others, in the same circumstances, appear 

 not susceptible. Climate, and food, and constitution will, therefore, all require to 

 be attended to in guarding against this pernicious evil. Amputation, and cutting 

 away all the diseased portion, should be resorted to on its first appearance ; a neg- 

 lected wound may even bring on this morbid condition of the tissue. Vitality 

 requires to be kept continually in action, especially during the active period of 

 growth ; if a stagnation is brought about by cold weather, it may form a favourable 

 state for the development and growth of the parasitical morbid cancerous state of 

 the tissue. If food is in excess, or any particular portion of the food, it may thus 

 become deleterious (most minerals found in the soil are needed in smaller or larger 

 quantities, it is only excess that renders them deleterious), and the vitality of the 

 tree may not be able to correct it, till, by accumulation, it forms a diseased can, 

 cerous state of the tissue : the more weak and languid the constitution, the more 

 apt it will be to succumb, and the more necessary will be the stimulus of heat to 

 enable it to overcome. The exudation of gum in stone fruit is unattended, to the 

 same extent, with the cancerous morbid state of parts exhibited by the apple and 

 pear ; but the disease appears to exist also in the sap, and to be ramified through 

 the branches, in the same way as canker, as may be often seen on cutting in to 

 arrive at its source. The small unripened shoots appear most liable, as being most 

 tender. The bark and alburnum appear first to be infected in these young shoots, 

 especially in the peach ; the young wood of which, being delicate from want of 

 ripening, appears unable to stand the severity of spring, gets discoloured in blotches, 

 and gum begins to exude. It would appear here that the disease arises from im- 

 perfectly-ripened tissue getting injured by severity of the weather, and affording a 

 nidus for it. In other cases, however, the gum begins to exude from parts to all 

 appearance sound and perfect, as if caused by a plethoric diseased state of the sap. 

 It is probable that, as in the cancer in the human body, which may be brought on 



