346 



SCIENCE 



[N. S. Vol. LIII. No. 1371 



of continuous selection in corn for certain special 

 characteristics, including both chemical and phys- 

 ical properties, have been carried on for many 

 years at the Illinois Agricultural Experiment Sta- 

 tion. Twenty-four generations of selection to in- 

 fluence the composition of the grain show very 

 marked responses, and from a single original va- 

 riety four diverse strains have been established, 

 namely, high protein, low protein, high oil, and 

 low oil. Similarly, high- and low-ear strains as 

 well as erect- and declining-ear strains have been 

 produced. Another example of this response to 

 selection has been the development of a two-eared 

 strain from an ordinary single-eared variety. In 

 like manner differences in yield have been induced 

 by similar methods of selection. These results all 

 go to show something of the possibilities of pro- 

 foundly modifying various characteristics by con- 



of shelled corn per acre of the Fi cross over the 

 better parent has averaged less for the last two 

 years than for the first four years of the tests in 

 the case of crosses with Minnesota No. 13. On the 

 basis of these results it appears that, if corn were 

 selected primarily on the basis of yield, the value 

 of Fj varietal crosses would be somewhat ques- 

 tionable. 



Bust mid tlie weather: H. L. Walster. At 

 Fargo, N. D.^ blue stem spring wheat averaged 7.1 

 bushels per acre in 5 seasons when rust epidem- 

 ics occurred, and 26.7 bushels per acre in 5 non- 

 rust seasons. The average minimal and maximal 

 temperatures by 10-day periods from the date of 

 seeding show the following differences as between 

 the respective 5-year periods: 

 Average Differences in Degrees F. for Each 10- 

 day Period after Seeding. Five-year Averages 



tinuous selection in a cross-fertilized plant such as 

 corn. 



First generation corn varietal crosses: Feed 

 Grippee. a brief review is made of the develop- 

 ment of the theory which accounts for the increased 

 vigor of Fi crosses. Experiments are reviewed in 

 which Fj corn crosses are compared with their par- 

 ents for yield of grain. Of 146 crosses, 113 ex- 

 ceeded the parental average in yield of grain and 

 84 exceeded the better parent. At the Minnesota 

 station 5 flint-dent crosses tested for a period of 

 two to six years yielded an average of 7.7 per cent, 

 more shelled corn per acre than either parent. 

 Particular attention is called to the cross between 

 Minnesota No. 13 and Squaw Flint which yielded 

 8.4 per cent, more shelled corn per acre than Min- 

 nesota No. 13, which is the higher yielding parent, 

 and was a week to ten days earlier in maturity 

 than Minnesota No. 13. Such a cross appears of 

 considerable promise for sections where early ma- 

 turity is an important factor. During the first 

 three years of the study a strain of Minnesota No. 

 13 was used which had been selected for type for 

 several years. In the latter years this strain was 

 selected primarily for yield. The increase in yield 



During rust years maximal temperatures rose 

 more rapidly and reached their highest point 

 sooner than in non-rust years. The average rain- 

 fall during April, May, June and July averaged 

 higher in rust years than in good years. When 

 high rainfall occurred in good years danger of 

 rust has been offset by low temperatures. When 

 excessively high temperatures have occurred in 

 good years, danger of rust has been offset by 

 droughty conditions. P. E. Brown, 



Secretary-Treaswer 



SCIENCE 



A Weekly Journal devoted to the Advancement of 

 Science, publishing the official notices and pro- 

 ceedings of the American Association for 

 the Advancement of Science 



Published every Friday by 



THE SCIENCE PRESS 



LANCASTER. PA. GARRISON, N. Y. 



NEW YORK, N. Y. 



Entered in the paet-a£cc mt Luicailtr. Pa., u Mcond dsM matter 



