Retrospective Criticism. 527 



varieties may sometimes be most vigorous ; but in general it will be found 

 the rule holds good, that the newest-raised seedlings possess most vigour. 



"911. Culture of the soil." Whatever mode of stirring the surface be 

 adopted, every facility should be given to the admission of atmospheric air, 

 heat, and moisture, and the bottom made as dry as possible by draining. The 

 great quantities of manure given to border crops of vegetables furnish perhaps 

 the most fruitful source of sponginess in the wood. 



"914. The potato when groivn in a garden is seldom found so mealy and 

 high-flavoured as ivhen groivn in afield, fyc." The land in gardens is generally 

 too rich for potatoes to be well ripened and dry ; more tubers are produced 

 of a large size, than the leaves and light are able to ripen and fill with starch. 



"1168. The mode of hearing, pruning, and training of the pear." If the 

 system of training noticed in this section, or something like it, were more 

 generally practised, there would be less need to complain of breast-wood. 

 On standard trees there is no occasion to go through forms of pruning to 

 produce spurs ; and, if the side branches were more encouraged in wall- 

 trees, we should have shorter shoots and natural spurs, and the tree would 

 be kept full of young wood to the centre, from the abundance of young 

 shoots to renew any that were getting naked. There should be greater 

 distance between the leading shoots, and abundance of side shoots laid in to 

 fill the wall ; though they might not all be got mathematically arranged, the 

 system of leaves and roots would be better balanced, the continual excite- 

 ment to produce which causes the great abundance of breast-wood. If the 

 greater part of them were nailed in, the tendency to produce fresh breast- 

 wood next year would be checked, and the tree become fruitful on the small 

 branches ; better fruit would be produced ; and the tree being full of young 

 wood, any part of it could be renovated at pleasure. 



" 1153. Diseases, insects, casualties, fyc, of the apple." 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 con- 

 geries of separate distinct beings, which have each an independent existence 

 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 

 fermentation 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 neglected 

 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 developement 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 cancerous state of the tissue : the 

 more weak and languid the constitution, the more apt it will be to succumb, 



