352 EXPERIMENT STATION EECOED. 



inconspicuous darkening of the bark, or later by an exudation of a brown rusty 

 liquid ; internally by a black layer below which the cortex is of a dirty red, 

 soon changing to a dirty claret color. The diseased cortex has a peculiar odor 

 which attracts boring beetles. The wood beneath is darkened by organisms 

 which follow the canker fungus. This diseased area, producing no latex, 

 spreads aroiuid. but more rapidly up and down the tree, which is usually 

 girdled and killed ; though cases of recovery have been noted recently, due to 

 causes not yet determined. 



The cause of Hevea canker is said to be a Phytophthora, which spreads 

 chiefly by means of zoospores, resting spores forming also in the diseased tis- 

 sues from which the canker has been known to spread even after partial heal- 

 ing of the diseased area. The fungus also attacks the pods, and may possibly 

 spread from these to the green branches, but not down these, it is said, to the 

 main stem. The same fungus is said to cause cacao canker, showing much the 

 same general progress and symptoms, and it is thought to attack breadfruit, 

 though this has not yet been proved experimentally. 



Treatment involves removal and destruction of affected, tissues, also of dis- 

 eased -fruits, and covering the wounds resulting with fungicides and protective 

 mixtures. Bordeaux mixture sprayed on the trunks is said to prevent attacks 

 of Hevea canker. See also previous notes (E. S. R., 17, p. 1085; 25, p. 46). 



Attempts to grow mistletoe (Viscum album) on m.onocotyledons and suc- 

 culent conservatory plants, E. Heinkicher (Anz. K. Akad. Wiss. [Vienna], 

 Math. Natvrw. Kl., 1912, No. 15, p. 236; abs. in Bot. Centhh, 122 (1913), No. 3, 

 pp. Jf-'i, 55). — On Opuntia parvula, V. album failed to establish itself, but a 

 partial growth was obtained on Cereus forbesH, the parasite effecting entrance 

 through the stomata and the substomatal spaces. Even in this case, however, 

 the intruded growths remained undifferentiated and thallus-like. The reaction 

 of these plants to invasion by mistletoe is said to resemble those set up in 

 defense against certain poisons, varying with different plants, the ordinary 

 hosts of mistletoe seeming to have established a tolerance for its products. 



Streak, a bacterial disease of the sweet pea and clovers, T. F. Manns and 

 J. J. Taubenhaus (Gard. Chron., 3. ser., 53 (1913), No. 1311, pp. 215, 216, figs. 

 2). — Studies on streak disease of sweet pea are said to show its identity with 

 that observed to attack several clovers. The disease is thought to be of bac- 

 terial origin and caused by Bacillus lathyri n. sp. It is said to be favored by 

 heavy dew and to be carried over in the soil, from which it may be spattered 

 on the plants by showers or sprinkling. The only treatment recommended is 

 such as may prevent its transmission in this manner, e. g., heavy mulching with 

 straw. Further details are to be given in a later publication. 



ECONOMIC ZOOLOGY— ENTOMOLOGY. 



Distribution and migration of North. Ainerican herons and their allies, 

 W. W. Cooke (U. S. Dept. Agr., Bur. Biol. Survey Bui. 45, pp. 70, figs. 21).— 

 This bulletin aims to give information as to the range of the several species, 

 especially the breeding range, and in regard to their migration. The data pre- 

 sented are believed to be sufficient to form a basis for protective legislation by 

 the States inhabited by the various si>ecies. While formerly widely distributed 

 in the United States and very abundant in certain localities, the herons In 

 recent years have everywhere been greatly depleted in numbers, chiefly because 

 of the demand for their plumage for millinery purposes. Several species of 

 egrets have, in fact, been almost exterminated. 



Maps are given which show the resident, breeding, and summer occux'rence 

 of the more important species. 



