DISEASES OF PLANTS. 245 



this being especially ti'ue as to phosphoric acid, and lime. An examination of 

 the mechanical texture of the soils indicated that there was a direct relation 

 between the clay content and yield performance. Better yields were also noted 

 on soils with a high humus content. The author points out, however, that much 

 of this humus was probably derived from the forests themselves. He is of the 

 opinion that emphasis should be placed upon the physical texture rather than 

 upon the amount of mineral food in soils and that failure of fertilizer experi- 

 ments in many forest soils is due to the poor water-holding capacity of the 

 soil. Such soils may be improved by the incoi-poration of humus, removal of 

 weeds, cultivation, etc. 



Pine manuring experiments on the dunes of the Kurischen lowlands, K. 

 Eackmann (Naturw. Ztschr. Forst u. Landio., 8 (1910), No. 11, pp. 513-522, 

 figs. 2). — The results of some preliminary experiments undertaken in the 

 Kurischen lowlands on the Baltic coast to determine the value of fertilizers for 

 promoting the ^'owth of pine seedlings in shifting sand dunes are reported. 

 The fertilizer ingredients were limited to varying proportions of basic slag, 

 kainit, and dried blood. 



Considerable improvement was noted in the fertilized seedlings over those 

 in unfertilized plats. The work is to be continued with a view of determining 

 the best individual fertilizer and the best combination of fertilizers for sand 

 dune culture. 



The life history of Parthenium (guaynle), J. B. Kirkwood {Amcr. Rev. 

 Trop. Agr., 1 (1910), No. 7, pp. 193-205, pis. 3). — In connection with his in- 

 vestigations relative to the propagation of guayule (Parthenium argentatum), 

 the desert rubber bearing plant (E. S. R.. 24, p. 151), the author collected some 

 data on its life history which are here discussed. Among other facts brought 

 out, it appears that guayule produces only about 17 per cent of fertile seed. 

 The explanation of this is being sought in embryological research. 



The rubber plants in northern Madag'asear, H. Jumelle and H. Pebrieb 

 (Agr. Prat. Pays Chauds. 10 (1910), No. 90. pp. 18^-196).— A further descrip- 

 tive account is given of the rubber yielding landolphias, mascarenhasias, and 

 plectaneias in northern JNIadagascar (E. S. R., 23, p. 246). 



The natural forests of Switzerland, H. and M. Bbockmann-Jebosch (Ber. 

 Schiceiz. Bot. Gcscll., 1910. No. 19, pp. 171-22.'t, map 1). — A contribution to the 

 knowledge of the plant geography of Switzerland with special reference to 

 timber trees. Consideration is given to the natural development of timber 

 stands in the past as well as the more recent development of timber stands as 

 influenced by human agency. 



An interesting phase of work in connection with the Davy School of 

 Forestry, L. L. Scott (Ohio State Hort. Soc. Ann. Rpt., ^3 (1910), pp. 93-96).— 

 Some of the more imiwrtant operations in tree surgery as practiced at the 

 Davy School of Forestry are described. 



DISEASES OF PLANTS. 



Eeport of the botanists, G. E. Stone and G. H. Chapman (MassacJiusetts 

 Sta. Rpt. 1909, pt. 1, pp. 69-72). — The work has been similar to that of other 

 years (E. S. R., 22. p. 245). Of the usual number of fungus diseases commonly 

 occurring in the State, several were jnore or less abundant, including rust on 

 apples, beans, qumces, and roses, peach leaf curl, beet scab, leaf spot of the 

 apple, and Alternaria leaf spot on muskmelons and watermelons. 



Keport on plant diseases from the Station of Vegetable Pathology of Bome, 

 G. CuBONi (Relasione sidle Malattie dcUe Piante Studiate durante il Biennio 

 1906-7. Rome: R. Staz. Patol. Veg., 1908, pp. VIII +80). —In a report on the 



