No. 2, June, 1921] PATHOLOGY 199 



potassium and phosphorus, when expressed on the basis of either the ash or the dry matter, 

 and of nitrogen in the dry matter, decrease; the percentages of calcium, however, increase. 

 The concentration of iron is greater in very young leaves, later decreasing slowly. The 

 concentration of the different constituents probably remains practically constant through- 

 out the period of normal maturity. Notable amounts of potassium and nitrogen are translo- 

 cated back into some portion of the tree as the leaves approach senility just preceding the 

 time of normal dropping. A part of the phosphorus also appears to be removed from the leaf 

 some time preceding normal maturity. The absolute content of magnesium does not decrease 

 as maturity approaches. Maximum amounts of potassium, phosphorus, and nitrogen are 

 contained in orange leaves by the time they are about 6 weeks of age. The absolute content 

 of calcium continues to increase until full maturity is reached. The highly calcareous nature 

 of the orange leaf is its most pronounced characteristic, the dry matter of the mature leaf 

 containing 5-6 per cent of calcium. — The composition of mottled citrus leaves differs from 

 that of normal leaves mainly in that the calcium content is smaller and the potassium, phos- 

 phorus, and usually the nitrogen contents are greater. The composition of mottled orange 

 leaves resembles that of immature leaves, although the percentages of ash and nitrogen in 

 the former are materially greater than in the latter. The sap of normal orange leaves becomes 

 increasingly concentrated and acidic, and when mature is especially rich in calcium. The 

 sap of mottled leaves contains sub-normal amounts of calcium and concentrations of potas- 

 sium and phosphorus fully twice as high as in mature normal leaves. Abnormally large 

 amounts of unionized acids occur in mottle-leaf sap. The composition of leaf spurs of 

 severely mottled trees varies from the normal in much the same way as the leaves; that of the 

 older wood is more nearly normal. The roots appear to contain considerably less than normal 

 amounts of potassium and phosphorus but an approximately normal amount of calcium. 

 The abnormalities in the composition of different parts of mottled citrus trees may be due, 

 in part at least, to the inability of the tree to satisfy its normal calcium requirements at criti- 

 cal periods. The possibility of correlating abnormalities in the composition of mottled trees 

 with conditions conducive to the disease is suggested. The significance of subnormal con- 

 centrations of calcium accompanied by supernormal concentrations of potassium and phos- 

 phorus in the leaves, especially in relation to the limiting of chlorophyll production, is not 

 known. No causal relationship may exist. If an inadequate supply of calcium conditions 

 the deficiency of chlorophyll, it probably does so indirectly. Mottle-leaf must be produced 

 experimentally before any explanation can be safely accepted. The leaves of affected trees 

 are not suffering from inadequate supplies of potassium, phosphorus, nitrogen, or iron. — 

 L. M. Massey. 



1377. Levine, Michael. Studies on plant cancers— II— The behavior of crown gall on 

 the rubber plant (Ficus elastica). Mycologia 13: 1-11. PL 1-2. 1921.— "Bacterium tume- 

 faciens inoculated into the apical internode of the branches, into the leaves, or main stem 

 of the rubber tree stimulates the development of a neoplasm in the region of inoculation. 

 The early stages in the development of the crown gall in Ficus elastica does not interfere with 

 the life of the plant as a whole nor does it interfere with the growth of the inoculated branches. 

 The crown gall in Ficus elastica after a number of months of active growth becomes hard and 

 dry and finally dies. The invasion of the stem by the new growth does not destroy the entire 

 conducting system of the stem, yet that portion of the stem above the gall dies, as well as a 

 considerable portion of the stem below. Cultures made from pieces of the crown gall and 

 stem above the gall yield only a schizomycete which in appearance is not unlike B. tumefa- 

 ciens and which when inoculated into the stem of young geranium and rubber plants produces 

 crown galls in the region of inoculation. It is possible that the crown gall cells or the crown 

 gall forming organisms are responsible for the progressive necrosis of the stem from the gall 

 upward and downward. The death of the plant due to crown gall is at least suggestive of the 

 death caused by malignant growth in animals." — H. R. Rosen. 



1378. L6pez Domingtjez, F. A. Has "yellow-stripe" or "mottling" disease any effect on 

 the sugar content of cane juice? Jour. Dept. Agric. Porto Rico 34:47-64. 1919 [1920].— 

 From a series of analyses of healthy cane and cane affected with the mosaic disease it is con- 



