One of the points to be kept in mind in the breeding work is to develop a type in which the fruits in any one cluster will ripen at the same time to prevent loss. The work of gathering the crop is tedious and could be much reduced in this way.
Enemies.
Fortunately the castor-oil plant has no serious pests as yet among either fungi or insects.
Manufacture.
The manufacture of castor-oil is largely concen trated at present in Jersey City and St. Louis. The former place presses much of the imported ma terial, while the St. Louis mills handle largely the production of the western states. The hydraulic press is the essential feature of these mills, as the common method is to crush by hydraulic pressure without any further treatment than the mere removal of foreign matter. The seeds are not decorticated, as is practiced with cotton seed in making cottonseed-oil. In some cases the seeds are steamed before pressing, but though this permits of more rapid extraction, it yields an oil of inferior quality for medicinal and other purposes.
Most of the mills leave in the residue 10 per cent or more of oil.
The residue, called castor pom ace, is a very good fertilizer material, but is poisonous to stock and cannot' be employed as cottonseed meal. In some places it is prized as a fertil izer for tobacco and other plants.
Uses.
Castor-oil is used largely in the dyeing of cotton goods, and for that purpose is converted by means of concentrated acids into a sort of soluble oil, which, because of the ready solubility of the alizarine dye in it, is often called alizarine-assis• taut or Turkey-red oil. It is not employed sc extensively in medicine as formerly, although among the rural population in the southern United States, and among the negroes particularly, it is still largely used. It is employed also in various
other ways, such as in the manufacture of "sticky' fly-paper and "glycerine" soap.
Literature.
A few references are here given :—The Castor Oil Plant, Miscellaneous Circular, United States Department of Agriculture, No. 1, pp. 1-4; F. C. Burtis : Castor Beans (1899), Oklahoma Ex periment Station, Bulletin No. 44, pp. 7-9 ; Crop and Forage Notes (1900), Oklahoma Experiment Station, Bulletin No. 48, p. 11 ; C. M. Daugherty: The Industry in Oil Seeds, Yearbook, United States Department of Agriculture (1903), pp. 411-426 ; The Castor-Oil Industry, Yearbook, United States Department of Agriculture (1904), 287-298 ; G. E. Hicks, Oil-producing Seeds, Year book, United States Department of Agricul ture (1895), pp. 185-204; G. L. Holter and J. Fields: Fertilizer Analyses of Castor Bean Plants (1897), Oklahoma Experiment Station, Bulletin No. 25, pp. 7,8 ; A Study of the Castor-Oil Plant (1898), Oklahoma Experiment Station, Bulletin No. 32, pp. 11-14 ; Determination of Oil in Castor Beans (1898 ), Oklahoma Experiment Station, Bulletin No. 32, pp. 14, 15 ; P. MacOwan, The Castor-Oil Plant, and Its Growth to Produce Machine Oil ( 1897 ), Agricultural Miscellanea, Cape of Good Hope, 13, pp. 483-487 ; G. E. Morrow and J. H. Bone, Castor Beans (1898), Oklahoma Experiment Station, Bulletin No. 33, pp. 13, 14; W. R. Shaw, The Improvement of the Castor Plant (1902), Oklahoma Experiment Station, Bulletin No. 54, pp. 1r10 ; J. G. Smith, Castor Bean, Hawaii Experiment Station, Press Bulletin No. 2, pp. 1, 2 ; A. Zimmermann, Die Ricinus-Kul tur, Der Pflanzer (1905), 1, pp. 76-88.