316 GENETICS [Bot. Absts. 



2128. Gourlay, W. Balfour, and G. M. Vevers. Vaccinium intermedium Ruthe* 

 Jour. Botany 57: 259-260. 1919. — This natural hybrid between V, mytrillus and V. vitis- 

 idaea was discovered in Britain by Robert Garner in Maer Woods, Staffordshire, and ex- 

 hibited in 1872, when it was thought to be a luxuriant state of V. vitis-idaea rather than a 

 hybrid. It was described by X. E. Brown in Jour. Linn. Soc. 24: 125, 1887, as V. intermedium 

 Ruthe, from specimens collected by T. G. Bonnet on Cannoch Chase. The plant is locally 

 very abundant in the Cannoch Chase area. Slight variations in different localities indicate 

 different acts of hybridization for each locality. Though the parent species must occur 

 together in many localities in England, only one other place has been recorded for the hybrid. 

 The writer asks if any circumstance at Cannoch Chase can be specially favorable for the pro- 

 duction and spread of the hybrid, and finds the answer in the constantly disturbed condition 

 of the soil over this area due to its having long been a military training ground. In unmo- 

 lested areas the parent species grow intermingled, but no hybrids are produced. The flower- 

 ing periods of the two parents are different, but overlap slightly. Some characters of the 

 hybrid are given. It is said to fruit sparingly. The fertility of the seed is now being tested. 

 — K. M. Wiegand. 



2129. Gowen, John Whittemore. A biometrical study of crossing over. On the mech- 

 anism of crossing over in the third chromosome of Drosophila melanogaster. Genetics 4: 

 205-250. 2 diagram. May, 1919. — Crossing over is a very variable phenomenon, the coeffi- 

 cient of variation ranging from 18 to 59 for single crossing over and from 67 to 110 for double 

 crossing over. This is a greater variability than has been observed in other physiological 

 or morphological characters. In the third chromosome, crossing over is not affected by ex- 

 ternal conditions (food, temperature, season, or bottle output) ; but it is affected by the genes 

 present. Selection for high and for low crossing over was unsuccessful, indicating that there 

 were no differences in modifying factors in the selection experiment. There is a positive 

 correlation between variations in crossing over in different regions of the third chromosome. 

 When allowance for this correlation is made, double crossing over is more likely to occur when 

 the two breaking points are 25 to 35 units apart than when the intermediate distance is greater 

 or less. — Alexander Weinstein. 



2130. Green, E. Ernest. As regards mutation in Coccidae. Trans. Entomol. Soc. 

 London 1918: 149-154. 1918. — The author holds that the resemblance of the scale insect, 

 Lecanium (Coccus) viride to an allied species, Pulvinaria psidii, is superficial. He points 

 out a number of differences in various organs and concludes adversely to the hypothesis of 

 K. Kunhi K ann an that one has arisen from the other by mutation. [See Bot. Absts. 3, 

 Entry 2149.]— Seu-all Wright. 



2131. Hadley, Philip. Egg-weight as a criterion of numerical production in the domestic 

 fowl. Amer. Nat. 53 : 377-393. 1 fig. Sept.-Oct., 1919.— In a small flock of White Plymouth 

 Rocks mean egg weight and mean flock production paralleled each other in the direction of 

 their fluctuations. That portion of flock showing greatest increase in egg weight, had also 

 the greatest mean annual production, while that showing the least had lowest mean annual 

 production. Possibility of use of increase in egg weight as an index of annual production is 

 suggested. — H. D. Goodale. 



2132. Harland, S. C. Notes on inheritance in the cowpea. Agric. News [Barbados] 

 18: 68. 1919. — Brief summary of paper to be published in Journal of Genetics. Announces 

 discovery of another color factor P involved in anthocyanin coloration of calyx, peduncle and 

 tip of young pod. This gene, two previously discovered genes, B and E, together with their 

 respective recessives, p, b, and e, behave as a series of multiple allelomorphs. [See also Bot. 

 Absts. 3, Entry 1003.]— R. J. Garber. 



2133. Harper, R. A. The structure of protoplasm. Amer. Jour. Bot. 6: 273-300. July, 

 1919. — No new theory is presented but the writer sees a movement away from the older idea 

 of the cell as an assemblage of physical units of various sorts to the conception of the proto- 



