Junk, 1920] GENETICS 323 



2163. Love, H. EL, and \V. T. Ceaig. Methods used and results obtained in cereal 

 investigations at the Cornell Station. Jour. Amer, Sue. Agron. 10: 146 1.77. / pi., 1 fuj. 

 April, mis. The n>w method of testing cereal crops in agronomic experiments as carried 

 out ;it Cornell University has been adopted because replicated row plats enable greatly in- 

 creased numbers to be handled on the same land with as greal accuracy as larger plats and 

 at much Less cost. The probable error is very greatly reduced us the number of replications 

 increases. It has been found that the chance of finding a superior Btrain in selection work 

 is dependent upon the number handled. In a hirge number of e:ises of different selections 

 the chance of finding a superior strain is a function of the numbers involved. Two general 

 methods of selection are used. Head selections are made in the field, taking care to select 

 from average growing conditions. These head selections are planted in head rows. The 

 head rows average 2\ feet in length for wheat and ."> feet in length for oats. The length of row 

 is dependent upon the number of kernels in the head selected. The second method of selec- 

 tion consists in planting selected strain with spacings of one foot each way. The superior 

 plants from these one foot rectangular plantings are taken over for plant row tests the fol- 

 lowing year. Head row tests become plant row tests the second year. A large amount of 

 elimination takes place in the head rows. In the plant row tests at least three-fourths of the 

 strains disappear the first year, the superior strains being mostly in the one-fourth retained. 

 The plant row tests are usually continued for three years, eliminating inferior strains each year. 

 Special methods of planting have been devised. The harvested bundles at harvest are 

 stored in a curing shed in the order of their field numbers. The length of the rod rows or 

 plant rows varies in such a way that a simple factor can be used to convert the grams per 

 row into bushels per acre. The oat rows are 15 feet. The grams are multiplied by 0.2 to 

 obtain bushels per acre. For wheat, the length is 16 feet and for barley 20 feet, the conver- 

 sion factor in each case being 0.1. For improvement work very few notes are taken. The 

 note work is reduced to those strains which are actually shown to be superior and are thus 

 kept. Rod rows do not give the same yields even when replicated, as are obtained by plants, 

 but the yields are of the same order. — In hybrid work with grains, the strains to be crossed 

 are planted in pots and grown in the greenhouse. This enables hybridization work to be 

 done at a season when outside work is not heavily pressing, reducing the danger of contami- 

 nation and injury by weather and enables the strains to be crossed to be brought closely 

 together, saving time in carrying pollen from the pollen parent to the pistil parent. Later 

 generations of hybrids are handled much as strain selection, except that segregations are 

 made largely in the laboratory. One variation from standard methods of operation in pol- 

 linating is that the tips of the glumes may be clipped to facilitate the operation of pollination. 

 When handled in the greenhouse, data show that there is practically no difference whether the 

 glumes are clipped or undipped. Brief mention is given of results obtained in crosses, but 

 the detailed results are published elsewhere.— Alvin Kezer. 



2164. Mackie, D. B. Navel Satsumas found in California. California Citrograph 4: 60. 

 / jig. Jan., 1919. — Writer recently reported in same journal the occurrence of navel fruits of 

 Satsuma mandarin in Japan. A reader of that article reports finding at Oroville, California, 

 navel fruits on certain branches of Satsuma trees. These fruits were seedless, and writer 

 suggests possibility of propagating a seedless navel strain of Satsuma. [Ordinary Satsuma 

 fruits are very largely seedless.] [See Bot. Absts. 3, Entry 2344.]—//. B. Frost. 



>t 



2165. Martin, John Nathan. Botany for agricultural students. 16 X 24 cm., x + 585 

 p., 488 fig. John Wiley & Sons, Inc. : New York, 1919.— Chapter 22 (p. 513-534), "Evolution, 

 includes paragraphs on variation, heredity, experimental evolution, continuous variation, 

 discontinuous variation or mutations, mutation in the evening primrose, the mutation theory 

 and Darwinism, causes of variation, somatoplasm and germplasm. Chapter 23 (p. 535- 

 556). "Heredity," is mostly devoted to a statement of .Mendel's discoveries and their confir- 

 mation, but also gives single paragraphs to the physical basis of heredity, active and latent 

 genes, and biometry. Chapter 24 (p. 557-565), "Plant breeding," contains brief sections on 

 selection, mass culture, pedigree culture, selection of mutants, hybridization, crossing and 

 vigor of offspring. — Geo. H. Shull. 



