CAN 



[ 1G3 ] 



CAN 



CANDY CARROT. AlhamdntaMatlhi'ola. 



CANDY-TUFT. Ibe'ris. 



CANEL'LA. (From canna, a reed ; the 

 form of the inner bark when peeled off. 

 Nat. ord., Canelluds [Canellacese]. Linn., 

 \\-Dodecandria 1-Monogynia.) 



This is the wild cinnamon of the West Indies, 

 FO called on account of its aromatic fragrance. 

 Canella, or white wood bark, yields, by distillation, 

 a warm, aromatic oil, which is often mixed with 

 the oil of cloves in the West Indies. Stove ever- 

 green trees ; cuttings of ripe shoots in sand, under 

 a glass, and in bottom-heat, in April or Mav ; 

 sandy loam and fibry peat. Summer temp., 60 

 to 80 ; winter, 50 to 55. 

 C. a'lba (white-woocZ-Aarfc). 40. White. W. Ind. 



1735. 



laurifo'lia (laurel-leaved). 30. White. S. 

 Amer. 1820. 



CANKER. This disease is accompanied 

 by different symptoms, according to the 

 species of the tree which it infects. In 

 some of those whose true sap contains a 

 considerable quantity of free acid, as in 

 the genus Pyrus, it is rarely accompanied 

 by any discharge. To this dry form of 

 the disease it would be well to confine 

 the term canker. In other trees, with 

 sap abounding in astringent or gummy 

 constituents, it is usually attended by a 

 discharge. In such instances it might 

 strictly be designated ulcer. This dis- 

 ease has a considerable resemblance to 

 the tendency to ossification, which ap- 

 pears in most aged animals, arising from 

 their marked tendency to secrete the 

 calcareous saline compounds that chiefly 

 constitute their skeletons. The. conse- 

 quence is, an enlargement of the joints 

 and ossification of the circulatory vessels 

 and other parts phenomena very analo- 

 gous to those attending the cankering oJ 

 trees. As in animals, this tendency is 

 general throughout their system; but 

 as is observed by Mr. Knight, " like the 

 mortification in the limbs of elderl 

 people," it may be determined, as to its 

 point of attack, by the irritability of that 

 part of the system. 



This disease commences with an en 

 largement of the vessels of the bark of a 

 branch or of the stem. This swelling 

 invariably attends the disease when i 

 attacks the apple-tree. In the pear th< 

 enlargement is less, yet is always pre 

 sent. In the elm and the oak sometime: 

 no swelling occurs ; and in the peach we 

 do not recollect to have seen any. The 

 swelling is soon communicated to the 

 wood, which, if laid open to view on it 

 first appearance by the removal of the 



ark, exhibits no marks of disease be. 

 'ond the mere unnatural enlargement. 

 n the course of a few years, less in 

 lumber in proportion to the advanced 

 age of the tree, and the unfavourable 

 circumstances under which it is vegeta- 



^ the swelling is greatly increased in 

 size, and the alburnum has become ex- 

 ensively dead ; the bark above it cracks, 

 rises in discoloured scales, and decays 

 even more rapidly than the wood beneath. 

 [f the canker is upon a moderately-sized 

 Dranch, the decay soon completely en- 

 ircles it, extending through the whole al- 

 ournum and bark. The circulation of the 

 sap being thus entirely prevented, all the 

 parts above the disease perish. 



Trees injudiciously pruned, or growing 

 upon an ungenial soil, are more fre- 

 quently attacked than those which are 

 advancing under contrary circumstances. 

 The oldest trees are always the first 

 attacked of those similarly cultivated. 

 The golden pippin, the oldest existing 

 variety of the apple, is more frequently 

 and more seriously attacked than any 

 other. The soil has a very considerable 

 influence in inducing the disease. If the 

 sub-soil be an irony gravel, or if it is not 

 well-drained, the canker is almost cer- 

 tain to make its appearance amongst the 

 trees they sustain, however young and 

 vigorous they were when first planted. 



Bruises and wounds of all kinds 

 usually are followed by canker in the 

 wounded part, if the tree is tending to 

 this disease. 



All these facts before us unite in as- 

 suring us that the canker arises from 

 the tree's weakness, from a deficiency in 

 its vital energy, and consequent inability 

 to imbibe and elaborate the nourishment 

 necessary to sustain its frame in vigour, 

 and much less to supply the healthy de- 

 velopment of new parts. 



It is quite true that over-luxuriant 

 trees are particularly liable to this dis- 

 ease; but over-luxuriance is really a 

 demonstration that the tree does not 

 digest and secrete its juices healthily. 



If over-luxuriance threaten to intro- 

 duce canker, the best remedy is to re- 

 move some of the main roots of the tree, 

 and to be particularly careful not to add 

 any manure to the soil within their 

 range. On the contrary, it will be well 

 if the continued exuberant growth shows 

 the necessity for the staple of the soil 

 to be reduced in fertility by the admix- 



