236 EXPERIMENT STATION RECORD. [Vol.38 



was superior to Pyrox, due to the greater cost of tlie latter and the less bene- 

 ficial results derived from its use. 



The significance of hybrid selections with rice and how they are orig- 

 inated, L. Koch {Tajsmannia, 27 {1916), No. 9-10, pp. 502-519, pis. 5).— Dis- 

 cussing the theory and practice of hybridization the author briefly reviews 

 the work of Van der Stok (E. S. R., 26, p. 435), begun in 1907, in hybridizing 

 rice varieties. 



Early rice planting as a means for augmenting the supply of irrigation 

 water, W. L. Mesman {Arch. Suikcriudu.^. Ncdcrland. Indie, 25 {VJlD, No. 2, pp. 

 S!,-.',0 ) .—The author presents data showing the saving in irrigation water made 

 possible by the early planting (before October 15) of early-maturing varieties of 

 rice on dry seed beds, withholding irrigation until after transplanting into the 

 open field. An increase of profits of about 50 per cent is claimed for this 

 practice. 



Population analyses and inheritance studies concerning self-sterility, self- 

 fertility, and sterility in rye, N. Heiubekt-Nilsson {Ztschr. Pflanzenziicht., 

 4 (r.UO), No. 1, pp. l-li4, fifis. 3). — The author reports observations on 242 

 parent plants and 114 of their progeny, all of which were subjected to various 

 mctliods of isolation. The study con.sisted of population analyses giving the 

 average percentage of fertility (the number of kernels per number of glumes) 

 of the variety- and of the pedigree-populations and of inheritance studies where 

 isolation had progressed through two or more generations. 



Methods of isolation and isolating materials are briefly discussed. A part 

 of the work was conducted with closed glass tubes (18 to 30 mm. in diameter) 

 into which the .spikes were inserted, the opening closed with cotton wrapped 

 about the stem, and the glass tube fastened to a stake driven into the ground 

 beside the plant. Other spikes were isolated by means of glass tubes the 

 closed ends of which had been cut off and the opening covered \\ith parchment. 

 In order to compare glass- and parchment-isolation with " normal " isola- 

 tion a few plants were grown in the open, where they were deemed adequately 

 isolated by reason of the fact that the experimental plats were at least 2 km. 

 distant from any other rye fields and the prevailing winds were from a direc- 

 tion from which there was no fear of foreign pollen infection. 



Considerable data are presented to compare the different isolating methods. 

 The setting of seed was noticeably depressed by artificial isolation, the average 

 fertility amounting to 7 per cent for the normal, 4 per cent for the parchment, 

 and 1 per cent for the glass-tube method. 



Different populations exhibited certain peculiar differences in regard to the 

 average fertility percentage, while hybrid populations were even more variable 

 than the parent and attained a higher fertility percentage. This was illustrated 

 in the hybrid strains Brattingsborg X Petkuser and Brattingsborg X Heinrich, 

 which gave an average fertility percentage of 7.7 with normal isolation and 2.6 

 with gla.ss-tube isolation. Petkuser populations, on the other hand, and indi- 

 vidual selections from Petkuser and Brattingsborg gave an average fertility of 

 0.5 per cent with glass-tube isolation and 3.8 per cent with normal isolation. 



Inheritance studies demonstrated that rye populations contain strongly self- 

 sterile, partly self-sterile, and self-fertile individuals. In the population re- 

 ceiving the most exhaustive study, an individual selection of Petkuser rye, of 

 73 plants observed 71 were self-sterile, 1 partly self-sterile, and 1 self-fertile. 

 The appearance of a self-fertile race was held to indicate that the character of 

 self -fertility was monohybrid, with self -sterility dominant. Self -fertile races 

 must therefore be immediately constant upon their appearance, this having 

 been demonstrated in one race through three generations. The self-fertile plant 

 mentioned above had a fertility percentage of 74.8 with normal isolation. Its 



