EEV. M. J. BERKELEY Otf VARIOUS FORMS OF CANKER. 25 



it is possible to trace the affection from its earliest stage, it will 

 sometimes be found that what at first sight might reasonably be 

 supposed to depend on insects has really a different origin, though 

 occasionally they may have aggravated the evil. 



On examining the affected tissues, little perceptible difference 

 occurs. In all cases the walls have become more or less flaccid, 

 though seldom broken up, and have assumed the brown tint due 

 to the presence of ulmates. The endochrome has often entirely 

 vanished, or has been deposited on the cell-walls under some 

 altered form. In moister tissues, where the cells are still turgid, 

 the contained liquid abounds in minute brown granules ; where 

 ducts or vascular tissues are involved, the cavity is sometimes 

 gorged with brown matter. The surrounding living cells are gra- 

 dually affected, and a complete or partial change takes place, so 

 that all neighbouring growths assume an altered form ; and the 

 lesion is of greater or less magnitude in proportion to the rapidity 

 with which the taint is communicated. The evil may sometimes 

 be arrested for years where pains are taken to remove carefully 

 the affected part and to secure the wound by some application 

 which may protect it from atmospheric influences. 



A notice respecting the cause and proper remedy for Canker, 

 by Mr. Rivers, appeared in the ' G-ardeners' Chronicle ' for Dec. 

 13, 1856, which seems highly worthy of attention. After stating 

 that certain varieties of apples, as the Hibston, Golden Pippin, 

 Newtown Pippin, Nonesuch, and Old Nonpareil, defy the utmost 

 care of the primer, he attributes the malady in these cases to 

 deep rooting, and he not only suggests as a remedy biennial re- 

 moving, but states that this system has answered in practice, and 

 that, where delicate varieties had been accidentally undisturbed, 

 canker prevailed. At the time of replanting, a quantity of charred 

 garden refuse or burnt earth was added to the soil with good 

 effect. Those varieties, however, which are of a less delicate con- 

 stitution need not be removed. 



In the same journal (June 13, 1857) is a notice by myself of a 

 pamphlet on Canker, by Mr. John Pearson, which is deserving of 

 especial attention. His remarks, however, apply more to stone-fruit ; 

 and it is well that cultivators should keep them in mind. Deli- 

 cate plants from warm countries cannot bear the wear and tear of 

 our changeable climate without care. The buds in half-ripened 

 wood are affected by alternations of wet and cold weather ; and he 

 has attempted to prove this by causing artificially a stream of 

 water to pass over the buds, and has induced in this way gum or 



VOL. IT. D 



