44 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



a small quantity of iron largely increases the development of 

 foliage, and consequently of tlie plant. In dealing with a myste- 

 rious disease such as canker, I should not leave out either iron 

 or magnesia. 



The following formula, which may be varied as circumstances 

 require, is suitable for the apple-tree : — 



Superphosphate of Lime .. . ... ... ... 12 parts. 



Nitrate of Potash 10 „ 



Chloride of Soda ... ... ... ... ... 4 ,, 



Sulphate of Magnesia ... ... ... ... 2 ,, 



Sulphate of Iron ... ... ... ... ... 1 ,, 



Sulphate of Lime ... ... ... ... ... 8 



This may be used at the rate of ^ lb. to the square yard over 

 the whole extent of soil within reach of the roots. It need not be 

 dug in ; one effect of the manure may be relied on — if it does not 

 cure canker, it will, at any rate, most certainly benefit the trees. 



I hope you will excuse me for having questioned some of the 

 conclusions of great horticultural authorities, but it seems to me 

 that some of these conclusions have been accepted without suffi- 

 cient examination, as being time-honoured traditions handed 

 down through many generations. Gardeners are, in this respect, 

 perhaps a little too conservative. 



I think much may be learnt by occasionally departing from 

 these traditions and making independent experiments in cultiva- 

 tion ; my own experience proves that many such experiments 

 resulted in failures, but there is full compensation if only one 

 useful discovery be made, or one error exploded. 



Discussion. 



Mr. Coleman asked if lime should be used in a caustic state? 



Mr. ToNKS replied that gypsum and lime rubbish were con- 

 venient forms, but lime in any state would serve the same 

 purpose. 



Mr. KouPELL presumed the lime should be slaked. He 

 had used lime freely to trees in conjunction with soot, and he 

 found the mixture imparted a much deeper red to the fruit and 

 a darker green to the leaves, and generally improved and bene- 

 fited the trees. Did he understand Mr. Tonks to say that it was 

 impossible for canker to be introduced to healthy trees through 

 a wound ? Or did he only mean that a healthy tree resists the 

 disease better than a weakly one ? For his own part, he con- 

 sidered that in this respect there was an analogy between plant 

 and animal life, and it was a well-known axiom in surgery that 

 if a wound was left open to the settlement and action of atmo- 

 spheric germs, it was far more liable to catch a disease than if it 

 was bound up. Hence he considered that any wounds made in 

 the bark of a tree by clumsy pruning, bad staking, by a ladder, 



