256 GENETICS [Bot. Absts., Vol. VI, 



difficulty of preservation arose among forms of orchard-grass. Few differences were seen in 

 timothy. Several types of English ray-grass were observed, but little is known of their 

 genetical behavior. [From anonymous review in Zeitschr. Pflanzenzucht. 7: 217. June, 

 1920.]— J. P. Kelly. 



1742. Raum, S. Zur Kenntnis des italienischen Raygrases unter besonderer Beriich- 

 sichtigung seiner Ziichtung. [Italian ray-grass with special reference to its breeding.] Fiih- 

 lings Landw. 1920 : 28-37. 1920. — Great differences were present in this grass as regards 

 length of life. Breeding at Weihenstephan of Lolium italicum comprised originally 64 indi- 

 vidual selections; two lines were finally retained — namely, No. 36, bearded, and No. 2, rather 

 beardless. The selected lines bloomed near each other, and after three selections there was 

 neither pure beardedness nor pure beardlessness. [From anonymous review in Zeitschr. 

 Pflanzenzucht. 7:217. June, 1920.]— J. P. Kelly. 



1743. Renner, Otto. Mendelsche Spaltung und chemische Gleichgewicht. [Mende- 

 lian splitting and chemical equilibrium.] Biol. Zentralbl. 40: 26S-277. June, 1920.— See also 

 Bot Absts. 6, Entries 1099, 1713, 1744. 



1744. Renner, O. Zur Richtigstellung. [By way of explanation.] Biol. Zentralbl. 40: 

 287. June, 1920. See preceding Entry 1743. 



1745. Roberts, Herbert F. The relation of protein content to variety types in American 

 wheat. Jour. Agric. Sci. 10: 121-134. May, 1920.— General discussion of the relation of 

 protein content in wheat to environmental conditions and to varieties. Mostly a survey 

 of the data from experimenters dealing with this subject. Long period between time of 

 flowering and time of ripening seed favors production of soft kernels with low protein content. 

 Water supply influences protein content to a greater extent than any other edaphic factor. 

 From data submitted, it is shown that the protein content of wheat rises as we pass from 

 moist eastern regions to the drier portions of the western states. Varietal differences do 

 exist which manifest themselves in higher protein content when grown along with other 

 varieties. A variety may have a higher standard deviation of protein content than others, 

 which indicates that this variety is not pure, or that it has a wide range of physiological 

 adaptation. The wheat varieties most widely grown are those which have the widest varia- 

 bility with respect to protein content. In breeding for general purposes, wheat strains 

 should be sought which show the widest variability in protein content; but in breeding for a 

 limited locality, wheat with a maximum protein content and with the least possible variation 

 in protein content should be sought. A bibliography of twelve citations is attached. — 

 W. E. Bryan. 



1746. Robertson, W. R. B. The presence of a longitudinal split in chromosomes prior to 

 their union in parasynapsis. Anat. Rec. 17:329. Jan., 1920.— Author's abstract of paper 

 read before the American Society of Zoologists, St. Louis, December 30, 1919.— It is usu- 

 ally stated in accounts of the synapsis stages that, following the telophases of the last sperma- 

 togonial division, a series of changes takes place which results eventually in the formation of 

 fine single threads (leptotene stage) that pair in the succeeding diplotene. The chromosomes 

 of Tettigidae, of which there are thirteen, exhibit a longitudinal split in each member during 

 the telophase and post-telophase stages previous to parasynapsis. Following the stages in 

 which there are thirteen split chromosomes come those in which the twelve autosomes of the 

 group pair side by side to form six threads, each of which is probably a four-strand structure — 

 a future tetrad. The plan of this presynapsis split in the members of a pair probably coincides 

 to a large extent with one of the planes of division in the succeeding tetrad. — The telophases 

 of somatic mitoses likewise show their chromosomes to be split before entering the so- 

 called resting condition. The split in a telophase chromosome of either a somatic or sperma- 

 togonia! cell-division probably dates to the resting period previous to the division just being 

 completed.— The presynapsis splitting of each conjugating chromosome may account for the 

 peculiar twisting. sometimes visible in. the two strands of one of the conjugants as compared 

 with those of the other in long or V-shaped tetrads. The possibility of such independent 

 twisting may have something to do with mechanics of "crossing-over." — W. R. B. Robertson. 



