No. 3, October, 1921] GENETICS 21 



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1340. Hakuison, J. W. Heslop. The inheritance of size in the crosses involving Oporabia 

 autumnata and O, filigrammaria. Vasciilum 7: 49-5G. 1921. — Mean wing length of the t> in 

 the geometric! subspecies 0. autumnata is IS mm., in O. filigrammaria 16 mm. (81 and 91 indi- 

 viduals respectively). Arranged in groups based on 0.5 mm. differences, the larger species 

 has its mode in "Class 10" ; the smaller in "Class 0." Both Fi and F2 hybrids are intermediate, 

 with modes in "Class 7" (means, 10 mm. and 16.8.5 mm.). Fi parents of mean size gave Fj 

 showing no increased, but rather lessened, variability, that is, with 4.9 as the coeflScient of 

 variation as compared with 5.1. F3 from unselected and mixed Fj parents tends to resemblg 

 F2 in size with slightly increased variability (especially true of ? 9 ), both in certain indi- 

 viduals showing intermediate coloration and in others constituting a peculiar group of segre- 

 gates as to color. Back-crosses similarly lend no support to the multiple-factor hypothesis, 

 fluctuating about means intermediate between those of the 2 pure types (that is, 16.5 mm. — 

 17.5 mm. in back-crosses, as compared with 16 mm. — 18.1 mm. in pure types) and within 

 narrow ranges. A comparative study of the 6 6 of the various families under consideration 

 corroborated the conclusions drawn from the examination of the 6 6 . — The results are "op- 

 posed to the multiple-factor theory of size determination unless it be granted that such factors 

 do not segregate pure in gametogenesis but rather enter the Fi gametes in an average or 

 contaminated condition." — /. H . Gerould. 



1341. Hartwell, Burt L. Thirty-first annual report of the Director of the Rhode Island 

 Agricultural Experiment Station. Bull. Rhode Island State Coll. 14: 57-65. 1919.— "The 

 inheritable character to laj' large eggs is not joined with high annual production; but a high 

 percentage increase in egg-weight, usually during April and September, does appear to be 

 associated with high annual production in numbers, at least for the first year." — Reciprocal 

 crosses between heavy Cornish fowl and light-weight Hamburgs are reported as having been 

 made in 1918 but results are not given. — William A. Lippincott. 



1342. Kelley, F. J. Substitutes for the words homozygous and heterozygous. Science 

 50: 458-460. 1919. — The common non-technical substitutes, pure, pure-bred, impure, 

 mixed, hybrid, mongrel, cross-bred, are descriptive of origin. Mendel himself used "con- 

 stant" in the sense of homozygous. This term is not subject to the above objection, and 

 inconstant maj' suitably be used for heterozygous. — John Belling. 



1343. Knibbs, G. H. The theory of large population-aggregates. Metron 1: 113-125. 

 1920. — The tendency of population to increase in geometrical progression may be modified by 

 other factors coming into operation. The rate of increase is affected by the natural resources 

 of the country, by technical skill, and by the standard of living. The possible density of 

 population is limited. The curve T = k t """* is suggested to describe the increase and 

 ultimate decrease of population. Pressure of population produces war. — John Rice Miner. 



1344. Knight, L. I. Physiological aspects of self-sterility of the apple. Proc. Amer. 

 Soc. Hort. Sci. 14: 101-105. 1917 [191S]. — In self-pollinated Rome Beauty apples the pollen 

 germinates properly, so that self-sterility is not due to pollen sterility. Asparagin present 

 on the style does not retard growth; it has an accelerating effect in artificial cultures of pollen. 

 The maximum growth of Rome Beauty pollen tubes in artificial cultures exceeded the length 

 required to reach from the stigma to the egg when Rome Beauty flowers are self-pollinated. 

 The maximum length of 10 mm. was attained by about 5 per cent of the tubes in 2 days, the 

 required length for Rome Beauty styles being 7 mm. Pollen is not sensitive to excess mois- 

 ture since Rome Beauty pollen germinates well in distilled water. No mechanical obstruc- 

 tion to the growth of pollen tubes was found. When Rome Beauty was pollinated with 

 Jonathan, the pollen tubes traversed the length of the style in 48 hours whereas tubes from 

 Beauty pollen were still growing in the style at the end of 120 hours when kept at a moderate 

 temperature; at higher temperatures, 80-90° F., 24 hours only were required to traverse the 

 style in selfed Rome Beauty. At the end of 120 hours the egg cell begins to disintegrate, 

 inhibiting fertilization. The relatively slow rate of growth of Rome Beauty pollen tubes 

 in Rome Beauty stylar tissue is suggested as an important factor in the self-sterility of that 



