270 GENETICS [BoT. Absts., Vol. VIII, 



was started from the 7th generation of series A and continued to Fu. The average percent- 

 age for these generations was 0.64. Here again the numbers were not large. Series B was 

 also selected for low crossover values. For the first few generations there was no effect. In 

 F? a pair gave 14.34 per cent. From Fs to Fu the percentage fluctuated between 10 and 23. 

 From Fi6 to F23 it varied around 10 and from F23 to F^g around 6. After F23 the line bred true 

 for low crossover values in mass cultures for 23 generations. — Series C was selected for high 

 crossover values. It was carried for 8 generations only and no progress was made. In F7 9 

 pairs gave low crossover values, less than 6 per cent. The authors interpret this to mean 

 that double crossing over had been induced, resulting in a decreased percentage. After mak- 

 ing several suggestions the authors concluded that "crossing over in the various regions of 

 the sex chromosome is probably controlled by multiple incompletely dominant factors." — 

 F. Payne. 



1908. East, E. M., and D. F. Jones. Genetic studies on the protein content in maize. 

 Genetics 5: 543-610. 8 fig. Nov., 1920. — Following a discussion of breeding plants for altered 

 chemical composition, the work of the Illinois Agricultural Experiment Station on high 

 and low protein content in maize is reviewed in detail. The conclusion is reached that the 

 individual seed rather than the entire ear should be used as the basis of selection. In a com- 

 parison between guarded self-pollinated ears and open or wind-pollinated ears, it was found 

 in the majority of cases that the seeds of the self-pollinated ear had the highest percentage 

 of protein. Pursuing the problem from this point, a test was made to determine the immediate 

 effect of pollination on the composition of the seed. It was found that in each of 32 compari- 

 sons the crossed seeds weighed more than the selfed seeds, supporting previous results. With 

 respect to the protein content the effect of cross-pollination is slight, 7 of the 32 cases showing 

 an increased percentage of protein but on the average a slight decrease. This decrease is 

 not accounted for entirely by the increase in weight of seed since the total amount of protein 

 also is increased. — When a mixture of pollen from high- and low-protein plants was applied 

 to plants of a high-protein strain a significantly higher percentage of protein was found where 

 both parents were high in protein. The protein content of different self-pollinated ears 

 borne on the same plant was tested and little difference found. — In a chemical analysis of 

 2nd generation seeds borne on 1st generation plants it was found that while the percentage 

 of protein was reduced the total amount per acre was increased due to the increase in yield. — 

 In conclusion the authors state that the protein content of the seeds is determined largely 

 by heredity although variations as high as 40 per cent may be caused by environmental 

 fluctuations. The number of differentiating hereditary factors involved cannot be determined 

 nor their method of inheritance described, but they are believed to be in excess of 5 or 6 with 

 the possibility of a smaller number of main factors and nimierous subsidiary ones. — Twenty 

 per cent of the protein of the seed is in the embryo and 80 per cent in the endosperm. The 

 notable variations appear in the endosperm. Heterosis increases the size of the seeds with 

 a consequent reduction in the per cent of protein. This is especially noticeable in seeds borne 

 by hybrid plants. Fi seeds when corrected for the influence of heterosis have a protein con- 

 tent intermediate between those of the parents, with perhaps a tendency to be closer to that 

 of the high-protein parent. — The factors borne by the male gamete are practically without 

 immediate influence on the protein content leading to the belief that the constitution of the 

 mother plant is the major determining factor. — If a high-protein strain is found to be desira- 

 ble it can be obtained more rapidly by the isolation and recombination of homozygous high- 

 protein strains than by the method of mass selection followed in the classical experiment at 

 Illinois. — /. H. Kempton. 



1909. FiRBAS, Heinrich. tjber die Erzeugung von Weizen-Roggenbastardierungen. 

 [The production of wheat-rye hybrids.] Zeitschr. Pflanzenzucht. 7: 249-282. Nov.,,1920. — Author 

 studied conditions affecting set of seed when wheat was crossed with rye. Flowers were 

 pollinated just after blooming and also at later dates, better results being obtained with the 

 earlier applications. Pollinations were made in heated and unheated rooms, under dry and 

 moist conditions, and at different times of the day; it is concluded that such external condi- 



