310 GENETICS [Bot. Absts. 



segregation in somatic tissue which Babcock and Lloyd show to be impossible since separa- 

 tion of chromosomes occurs in heterotypic mitosis and does not normally occur during divi- 

 sion of somatic cells. A more probable explanation is a factor mutation occurring in a single 

 somatic cell such that all cells descending from the mutated cell would produce the chimera. 

 The same theory applies to phenomena which occur in many plant genera. Among the Fj 

 grains of the cross, Extra Early Adams white dent corn with Black Mexican sweet corn a 

 half purple and half white sweet grain was found. If the progeny from this grain gives evi- 

 dence that the embryo is homozygous for the purple color, then the chimera can only have 

 come about by somatic mutation. [See Bot. Absts. 2, Entry 930.] — M. J. Dorsey. 



2105. Correns, C. Die Absterbeordnung der beiden Geschlechter einer getrenntge- 

 schlechtigea Doldenpflanze (Trinia glauca). [Order of death of the two sexes in a dioecious 

 umbelwort (Trinia glauca).] Biol. Zentralbl. 39: 105-122. 3 fig. Mar., 1919. — Dioecious, 

 biennial Trinia glauca shows one-to-one sex ratio just before bloom. Before this, mortality 

 of males and females is equal. With beginning of bloom the death rate of males becomes 

 nineteen times death rate of females. Since this ratio remains constant throughout period 

 of bloom, death cannot be due to completion of life cycle but to differences in resistance to 

 disease observed in both sexes. — Helcne Boas Yampolsky. 



2106. Cowgill, H. B. Cross-pollination of sugar cane. Jour. Amer. Soc. Agron. 10: 

 302-306 1918 — 'This paper contains a brief historical review of methods used in breeding 

 6Ugar cane. The difficulty of emasculating sugar cane flowers and securing crosses by hand- 

 pollination is explained and several methods used by others to secure cross-pollination are 

 mentioned. The method devised by the author for use in Porto Rico is described: cheese 

 cloth bags, 18 inches in diameter and 48 inches long, and held extended by heavy wire rings 

 are placed over the panicles. One ring is placed at the upper end of the bag and the other 

 16 inches from the lower end. This 16 inch apron may be drawn together around the stem 

 below the panicle and tied so as to keep out undesirable pollen. The bags are supported by 

 bamboo poles and placed in position when panicles first appear. Some varieties of cane are 

 almost completely self-sterile. On account of this fact it is possible to cross them by placing 

 the panicle of some other variety in the bag in position so that the pollen when shed will be 

 carried to stigmas. Several different crosses and combinations have been made in this way 

 and a thousand or more hybrid seedlings secured each year for three years. That these seed- 

 lings were true hybrids was evidenced by the fact that characters of both parents were found 

 combined in them. — H. B. Brown. 



2107. Cowgill, H. B. Studies in inheritance in sugar cane. Jour. Dept. Agric. Porto 

 Rico 2: 33—41. 1918. — Seedling sugar canes show a certain degree or resemblance to their 

 parents, particularly in regard to color. There is wider variation in seedlings than in plants 

 from cuttings of the same variety. Certain varieties produce better seedlings than others, 

 and some produce a larger percentage of abnormal seedlings. In crosses a recombination of 

 characters of the parents appears to be produced in some seedlings. This is considered to 

 be due to dominance of certain characters derived from each parent. Only slight difference 

 in sugar content has been observed between groups of seedlings produced from different var- 

 ieties. — S. C. Harland. 



2108. Darbishire, F. V. Sugar beet seed. Jour. Soc. Chem. Ind., Rev., 38: 21. 1919. 

 — Danger of depending on a foreign country for essential raw materials illustrated by fact 

 that in United States the beet sugar industry needs annually about 6000 tons of seed, 4000 tons 

 of which was formerly brought from Germany. Progress in seed production in this country 

 since 1915 is noted, production in 1917 reaching 2773 tons. German grades of super-elite, 

 61ite and commercial seed are described. Reason for requirement of five years (in Europe 

 and eastern America) is explained. Effort to develop sugar beets with single-germ seed-balls 

 is mentioned; also importance of working for disease resistance. — E. B. Babcock. 



