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



northern Burma and to have been imported into China from this district at an early date. 

 This conclusion supports the contention of Dr. Laufer that maize entered China from the 

 West and not the East. — J. H. Kempton. 



1648. Collins, G. N., and J. H. Kempton. Ateosinte maize hybrid. Jour. Agric. Res. 

 19: 1-38. PL 1-7. 32 fig. 1920. — A study of a hybrid between Florida teosinte and a small 

 variety of maize known as Tom Thumb pop. Besides possible practical agricultural applica- 

 tions of the product, such a cross is of especial interest genetically because of the rare oppor- 

 tunity of securing fertile hybrids from such widely divergent parent forms. Characters of the 

 Fi were mainly intermediate. Observations were taken on 33 character pairs of the Fj, being 

 considered in groups according to certain morphological or physiological relationship. 

 Results are presented graphically in form of distribution curves. There was the greatest 

 freedom of recombination and, barring one or two exceptions, little evidence of alternative 

 or Mendelian inheritance. — L. H. Smith. 



1649. Conklin, Edwin Grant. The mechanism of evolution in the light of heredity and 

 development. V. The cellular basis of ontogeny and phylogeny. Scientific Monthly 1920: 

 269-291. 11 fig. Mar., 1920. — A summary and restatement of present-day conceptions of the 

 cell in reference to ontogeny and phylogeny. The physical basis of heredity and of evolu- 

 tion is contained in the germ cells, which form the only living bond between generations and 

 between species. There is "no fundamental distinction" between germ cells and somatic 

 cells. Up to an undetermined critical stage, either may under certain conditions give rise 

 to the other. There are, however, marked morphological and physiological differences 

 between the germplasm (nucleus) and somatoplasm (cytoplasm). The individuality of the 

 chromosomes "is no longer a mere hypothesis, but an established fact;" and every chromo- 

 mere will probably be found to have a distinct and continuous entity, the number remaining 

 constant for every species. The smaller units which enter into the organization of the cell 

 are alive, as is the whole cell. These divide equally, not differentially. Variations in combi- 

 nations of vital units are responsible for "all forms of differentiation, variation, and evolu- 

 tion." The problem of the mechanism of heredity must be studied both from the side of 

 cytology and of genetics. All the evidence at hand strengthens the assumption that genes 

 have a linear arrangement in the chromosomes. A statement and brief discussion of the 

 facts, as known today, regarding mitosis in general, meiosis, fertilization, sex determination, 

 sex-linked characters, linkage, "cross-overs," etc., lead clearly to the conclusion that the 

 inheritance units or genes or Mendelian factors are carried in the chromosomes. — Margaret 

 C. Ferguson. 



1650. Conners, C. H. Some notes on the inheritance of unit characters in the peach. 

 Proc. Amer. Soc. Hortic. Sci. 16: 24-36. (1919) 1920. — Blossoms of peaches are classified as 

 large, medium, and small. Of 50 trees of a self-pollinated small variety, 46 bore small-sized 

 blossoms. Crosses between small- and large-blossom varieties gave first generation seed- 

 lings with medium-sized blossoms. — Varieties with medium-sized blossoms, when self-polli- 

 nated, gave large-, medium-, and small-blossom seedlings in percentage ratios of 18.6, 58.2, 

 and 23.3, respectively. — Medium crossed with small gave large-, medium-, and small-blossom 

 seedlings in percentage ratios of 4.5, 61.4, and 34.1, respectively. Medium crossed with large 

 gave large-, medium-, and small-blossom seedlings in percentage ratios of 36.5, 58.7, and 4.9, 

 respectively. — The breeding behavior for color of fruit, date of ripening, and freestone versus 

 clingstone, is given for various "selfed" varieties and crosses. — Fred Griffee. 



1651. Copeman, S. Monckton. Experiments on sex determination. Proc. Zool. Soc. 

 London 1919:433-435. Feb., 1920. — Rabbits were semicastrated or semi-spayed either on 

 the left or the right side, and then bred with animals which had had a similar operation or 

 with entire animals of the opposite sex. This was done in an attempt to determine whether 

 the right or left gonads were prepotent in determining the resulting sex of the offspring. 

 The results were contradictory, and the general conclusion was that the reproductive cells of 

 a gonad may give rise to either sex. — D. D. Whitney. 



