220 GENETICS [Bot. Absts., Vol. V, 



wild Texan species which was introduced into cultivation in 1835. — Importance of bud sports 

 is noted in the case of the Sword fern and variegated Coleus and also with the citrus fruits. — 

 Discusses modern method of plant breeding with respect to pedigree culture, and summarizes: 

 "In practical application, the methods of plant breeding are (1) to maintain in a highly- 

 productive condition races whose qualities make their cultivation desirable, (2) to recognize 

 and preserve new characteristics which may lead to further improvement, (3) to combine 

 qualities of different strains into one strain through crossing, and (4) to induce hereditary 

 variation through hybridization. Plant breeding aims to regulate, to control, to direct, 

 and to utilize the processes of heredity and variation." — C. E. Myers. 



1666. Streeter, Geo. L. Formation of single-ovum twins. Bull. Johns Hopkins Hos- 

 pital 30: 235-238. 4 fig- 1919. — The mature ovum here referred to is the one previously 

 described by the same author (Carnegie Inst. Washington Pub!., 272.) The ovum, which 

 is about 17 days old, contains two embryos. One of these is considerably more advanced 

 than the other. The primary embryo is in the primitive-groove stage, and has an embry- 

 onic plate 0.92 mm. long by 0.78 mm. wide. Two small vesicles slightly separated from each 

 other are found in the loose mesenchyme in the posterior region of the body-stalk. These 

 two vesicles represent the Amniotic vesicle and the yolk-vesicle, respectively, of the smaller 

 twin. This small embryo is undoubtedly abnormal. By comparing this ovum with the 

 Miller specimen and the Bryce-Teacher specimen, the author is able to indicate how in all 

 probability monozygotic, or identical twins are formed. The ovum is one of unusual interest, 

 in that it shows the youngest stage of twinning so far recorded for the human species. — /. T. 

 Patterson. 



1667. Strong, Leonell C. Roughoid, a mutant located to the left of sepia in the third 

 chromosome of Drosophila melanogaster. Biol. Bull. 38: 33-37. Jan., 1920. — New mutant, 

 characterized by roughened eyes, found to lie to the left of sepia, which had been furthest to 

 the left of known third-chromosome loci. Roughoid sepia crossover value of 24.9 was obtained. 

 — A. H. Sturtevant. 



1668. Stuckey, H. P. Work with Vitis rotundifolia, a species of Muscadine grapes. Geor- 

 gia Agric. Exp. Sta. Bull. 133 : 60-74. 4 pi- (colored) , 8 fig . Dec, 1919. — Work with rotundifolia 

 was started at the Experiment Station in 1909. A history of workers with this species of 

 grape is given. The work at the Station bears out the fact that Vitis rotundifolia is self- 

 sterile, though the fruiting vines produce pollen. This pollen is infertile due to a degenera- 

 tion of the generative nuclei. Work with more than two thousand seedlings which have been 

 brought into bearing shows that approximately one-half are males and one-half are females. 

 The male vines are more vigorous in growth and a larger percentage of these produce flower 

 before the female vines. In more than one thousand bearing vines, it was found that the 

 color of the tendrils and new growth correspond to the color of the fruit; vines having red or 

 reddish green tendrils bear black or reddish black grapes, while those with green tendrils, 

 internodes and new growth, produce light or amber-colored fruit, as the Scuppernong. Male 

 vines fall into these two groups just as the females except they bear no fruit. Black is domi- 

 nant over white and latter color is pure recessive. A formula showing crosses between plants 

 heterozygous for black, red and white is given. Thomas X dark male produced only plants 

 with dark fruit, but seedlings from Scuppernong X dark male produced plants of different colors 

 of fruits. Certain male vines were prepotent for quality. In Flowers X light male no. 1, out 

 of 41 seedlings, only one produced fruit inferior in flavor to the Flowers; the others were supe- 

 rior. From nine vines of Flowers X Black No. 1 , only one produced fruit equal in flavor to the 

 Flowers. New varieties described are Hunt, Irene, November, Qualitas, Spalding and 

 Stuckey. It is further stated that pruned vines growing by the trellis system, when in good 

 bearing should produce 50 to 60 pounds or about a bushel of fruit per year. Test of various 

 strains of Scuppernongs, which is the most common variety of Vitis rotundifolia, demon- 

 strated that nurserymen have made some effort to eliminate poor-bearing types and those 

 untrue to name. Last page of the bulletin details methods of planting and pruning, and uses 

 of the fruit.— T. H. McIIatton. 



