582 



NATURE 



[December 30, 1920 



lished in the Quarterly Journal of Forestry (vol. xiv., 

 1920, p. 253). 



The joint discussion with the Botanical Section on 

 " Plant ami Soil Survey Work " brouj;ht forward an 

 interesting group of papers on both the chemical and 

 botanical sides. Mr. G. W. Robinson (Bangor) 

 described the results of his soil survey work in North 

 Wales, and showed that attempts to classify the soils 

 according to the geological formation from v^-hich 

 they were derived had proved unsatisfactory. This 

 was partly due to large areas having been obscured 

 by glacial drifts, and also to the fact that, even in 

 the case of soils derived from the underlying rock, 

 the variety of soiK'types is by no means so great as 

 that of rock types. 



The soils have been classified into twelve types, 

 four of which are composed of soils mainly derived 

 in situ from the underlying rock, while the other types 

 include transported soils such as drifts and alluvia. 



Mr. E. A. Fisher dealt with the important question 

 of soil acidity, and suggested doubts as to the trust- 

 worthiness of the ordinary methods for determining 

 the "lime requirements " of a soil. 



Prof. R. G. Stapledon described his "Surveys of 

 Grassland Districts " ; while Miss W. H. Wortham 

 gave a summary of the results of a botanical survey 

 of North Carnarvonshire and Anglesey. 



Sir Daniel Hall, Messrs. C. G. T. Morison, T. J. 

 Jenkin, C. T. Gimmingham, and R. Alun Roberts, 

 Miss E. N. Miles-Thomas, and others took part in the 

 discussiop which followed. Sir Daniel Hall said that 



there did not always appear to be a clear conception 

 as to the object of the work. He suggested the 

 simplification of methods, if possible, and a closer 

 attention to the economic side of the question. 



From the discussion two points emerged : (i) The 

 soil chemists were quite agreed that the time had 

 come for a revision of the methods of soil sampling 

 and analysis at present in use, and it was felt that 

 it was not desirable to embark on any extensive new 

 work before this was done. (2) It was evident that 

 there was need for a much closer co-operation 

 between the soil chemist and the plant ecologist, 

 both in planning survev work and in carrying it out. 

 This is more true of England than of Scotland. 



It was resolved to appoint a joint committee repre- 

 senting plant ecologists and soil chemists to consider 

 and report on the whole question. 



At the closing meeting Mr. G. S. Robertson 

 described the results of his most recent investigations 

 on manuring with ground rock-phosphates. He 

 referred to the increasing demand for phosphates both 

 at home and abroad and toi the difficultv of main- 

 taining the supply of superphosphates and slag. The 

 experiments showed that ground mineral phosphates 

 gave results which compared very favourably with 

 the returns given by the old basic Bessemer slags. 



.'\mongst the other papers read were " Experiments 

 on Green Manuring," bv H. J. Page; "The Sugar- 

 Content of Straw," by S. Honre Collins; and "The 

 Varieties of t)ats," by C. B. V. Marquand. 



Alexander Laider. 



Studies of Heredity. 



MR. C. C. LITTLE has studied {Journal of 

 Genetics, vol. viii., 1919, pp. 279-90) colour 

 inheritance in cats, with special reference to black, 

 yellow, and tortoiseshell, and gives an explanation — 

 not a very easy one — of the rare occurrence of tortoise- 

 shell males which may be either sterile or fertile. 

 The genetic constitution of the normal colour varieties 

 of cats as regards yellow and black pigmentation 

 appears to be as follows : B = a factor producing 

 black pigmentation, Y = a factor which restricts black 

 from the coat, and y = a factor allelomorphic to Y 

 and hypostatic to it, allowing black pigment to extend 

 to the coat. Mr. Little also discusses (Science, vol. 11., 

 1920, pp. 467-68) a curious case in the Japanese waltz- 

 ing mouse of hereditary susceptibility to a transplant- 

 able tumour. He concludes provisionally that from three 

 to five factors — probably four — are involved in deter- 

 mining susceptibility to the mouse sarcoma ; that for 

 susceptibility the simultaneous presence of these 

 factors is necessary ; that none of these factors is 

 carried in the sex (x) chromosome; and that these 

 factors Mendclise independently of one another. In 

 another paper (Ainer. Naturalist, vol. liv., 1920, 

 pp. 267-70) the same investigator criticises Dunn's 

 suggestion that there is a linkage between the genes 

 for vellow and for black in mice, and shows that the 

 facts may be explained by assuming that yellow, 

 when present, hampers the action of a lethal factor 

 in much the same sort of way that it hampers the 

 activity of the black-forming factor in the skin and 

 hair. In a note on "Some Factors Influencing the 

 Human Sex-Ratio " (Proc. Soc. Exper. Biol, and Medi- 

 cine, vol. xvi., 1919, pp. 127-30) Mr. Little concludes: 

 (i) That a significant excess of males is observed in 

 the progeny of human matings involving racial crosses 

 as compared with matings within the race; (2) that 

 racial crosses between the European races studied 

 (Italian and Spanish) will produce in the first hybrid 

 NO. 2670, VOL. 106] 



generation a significant excess of males (which will 

 be economically important to the United States) ; and 

 (3) that there are significantly fewer stillbirths among 

 the progeny of the hybrid matings studied than among 

 the pure matings. In another paper {Amer. Naturalist, 

 vol. liv., 1920, pp. 162-75) Mr. Little deals with 

 exceptional colour-classes in doves and canaries. 

 These have been explained on the hypotheses of 

 "partial sex-linkage " and "non-disjunction," but the 

 author thinks it is more legitimate to suppose a fac- 

 torial change from one gene to its allelomorph, 

 perhaps as the effect of "intergenic and intra-cellular 

 environment." In a note on the origin of piebald 

 spotting in dogs (Journal of Heredity, vol. xi., 1920, 

 pp. 1-4, 3 figs.) Mr. Little deals with two cases in 

 dogs which give direct evidence as to the origin of 

 spotted individuals, and suggests that a spotted race 

 may arise from a self-race, by mutation, without 

 passing through a series of minute gradations directed 

 by selection. 



Dr. C. B. Davenport (Proc. Nat. Acad. Science, 

 vol. iv., pp. 213-14) deals with an hereditary tendency 

 to form nerve-tumours (multiple neurofibromatosis). 

 Proliferations of the connective tissue-sheaths of 

 nerves result in numerous sessile or pedunculate 

 swellings. The course of the disease, which is rare, 

 is influenced bv metabolic changes in the body. There 

 is sometimes an associated production of pigmented 

 spots in the skin. There is evidence that the disease 

 may occur in successive generations, and that it 

 behaves as if it were a dominant, occurring in about 

 50 per cent, of each affected fraternity. " The fact 

 that neurofibromata have an inheritable basis 

 strengthens the view that cancers in general have 

 such a basis." In another paper (Journal of Heredity, 

 vol. X.. 1919, pp. 382-84) Dr. Davenport reports a 

 case of a Cleveland familv where a tendency to 

 multiple births has appeared in each of four successive 



