FIELD CROPS. 333 



It is stated that when a variety is grown for a considerable time on the same 

 soil special strains with regard to skin thickness are developed, and when these 

 are then grown on a different kind of soil this character is more or less last- 

 ing. Kainit, common salt, and nitrate of soda exerted an unfavorable influ- 

 ence, and superphosphate a favorable influence on the development of the skin. 



The stone cells occurring in many varieties are not regarded as indicating 

 a high degree of maturity, but as a variety characteristic pointing to the origin 

 of the strain from a variety containing these cells or as being the result of hy- 

 bridization. In order that thick-skinned potato varieties may be secured it is 

 recommended that the seed be obtained from those localities in which varieties 

 with thick skin have been grown for a considerable length of time. It was ob- 

 served that on soils which produced thin-skinned potatoes the use of phosphoric 

 acid as a fertilizer increased the resistance of the skin. In addition to the 

 absolute thickness of the skin in determining its resistant quality, the arrange- 

 ment of the cork cell layers is also of importance. 



The influence of cross- and self-fertilization on the sugar content in the 

 sugar beet, K. Andrlik, V. Bartos, and J. Urban {ZtscJir. Zuckerindus. 

 BoJimen, 32 (1908), No. 7, pp. 373-3S7). — In a series of experiments here re- 

 ported the influence of cross-fertilization on the sugar content of the progeny 

 was observed in numerous cases. The progeny of self-fertilized plants showed 

 in part a tendency to degenerate, many individuals having yellow and red spots. 

 The progeny of self-fertilized rich beets was lower in weight than the progeny 

 from self-fertilized beets low in sugar. The beets resulting from cross-fertiliza- 

 tion stood in average weight about halfway between the beets derived from 

 rich and poor mother beets. 



The essential mineral constituents of the sugar cane, T. Murakami (In- 

 ternat. Sugar Jour., 10 ( 1908), No. 112, pp. 172-175). — A chemical study of sugar 

 cane is reported. 



The relative results indicate that the nitrogen content decreases and the total 

 ash increases as the cane grows. Phosphoric acid and potash appeared to de- 

 crease per 100 parts of ash but were always constant per 100 parts of cane. Tlie 

 ratio of soda to potash was found to be constant. The only ingredients that 

 increased were oxid of iron, alumina, sulphuric acid, and perhaps silica. A cer- 

 tain ratio was observed between lime and magnesia, but this varied slightly as 

 the cane matured. The ratio between phosphoric acid and potash is determined 

 as 1 : 20, which does not change during the growth of the plant. 



The results further indicate that a maximum crop and a maximum sugar con- 

 tent are obtained on a rich soil in which the essential ingredients are distributed 

 in an available form. It is recommended that lime be applied with nitrogen, 

 phosphoric acid, and iwtash in order to maintain the proper ratio between 

 lime and magnesia. 



Cultivation of the sugar cane in Peru {Intcniat. Sugar Jour., 10 (1908), 

 A'o. 112, pp. 177-185). — This article is a translation of a treatise on sugar cane 

 culture in Peru by F. T. Sedgwick. 



Virginia tobacco experiments, E. H. Mathewson, B. G. Anderson, and R. 

 P. Cocke (Virginia Sta. Bui. 175, pp. I.'i5-171, figs. 9). — These experiments are 

 carried on cooperatively by the Bureau of Plant Industry of this Department 

 and the Virginia Experiment Station. An earlier report on this work has 

 already been noted (E. S. R., 19, p. 335). 



The bulletin outlines a crop I'otation for the dark tobacco belt of the State 

 and reports the results obtained in an unfinished rotation. The succession of 

 crops suggested is based upon tobacco as the leading crop, being followed by 

 wheat, which in turn gives place to gx'ass. After the grass crop corn is grown, 



