1911.] PUBLIC DOCUMENT — No. 31. 151 



r.ppearaiicc is iioticeablo only on the upper surface of the leaf, 

 and appears to extend only through the palisade cells. As yet 

 no investigation has been made with reference to its character, 

 but from its appearance under the microscope it is thought that 

 it may be due to the breaking down of the chlorophyll granuk^s 

 as a result of the diseased condition of the leaf. 



Under all conditions of disease, however, the leaves are mucli 

 distorted and stilf, and often very badly curled, usually with the 

 edges rolled up over the leaf, and never possessing the flexi- 

 bility of healthy, normal leaves. 



CEdema is perhaps the least liable to be confounded with 

 other physiological troubles as its appearance is more strongly 

 characteristic. Only a brief description will be given here, as 

 this trouble does not enter into the discussion in this paper. 

 Usually the leaves, as a whole, hang pendent, but the leaflets 

 curl strongly upward ; on close examination it is found that the 

 veins, midrib and surface of the leaf show elevated more or 

 less frosty areas, somewhat rescndjling the masses of conidia of 

 some of the Erysyphsc ; although in mild cases this condition is 

 not striking, but the leaves usually have a more or less pearly 

 luster at some stage of its development. The epidermal cells are 

 very much enlarged in these areas and turgid, and the chloro- 

 phyll-bearing cells are also greatly changed. For a detailed 

 description and discussion of this trouble no better work can 

 be found than that of G. F. Atkinson.^ 



It can be seen from these brief descriptions that unless care 

 were exercised it might be easy to confound these troubles, espe- 

 cially in the case of the first two. Keeping this in mind we 

 will pass on to a more detailed description of the malformation 

 of stump growth subsequent to the l^urning off or cutting do\\nr 

 of large trees. 



The malformation appears to be worst in the first two or three 

 seasons' growth, the sprouts outgrowing the trouble as their age 

 increases. From our observations this trouUe appears to occur 

 in two distinct forms : first, as an abnormal growth of stem and 

 leaves, they sometimes reaching a size five to ten times that of 

 normal young plants of the same species. This form of the 



> N. Y. (Cornell Univ.) Agr. Exp Sta., Bui. No. 53, "(Edema of Tomato." 



