464 



NATURE 



[June 10, 1920 



system of scholarships, held on the double condition 

 of carrying out in the museum research work and 

 curatorial work satisfactory to the professor and the 

 curator respectively." 



An interesting addition to the literature on the 

 subject of the relationship between light and plant- 

 growth appeared recently in the Journal of Agricul- 

 turcd Research (vol. xviii., No. ii, March, 1920). In 

 this paper W. W. Garner and H. A. Allard discuss 

 the effect of the relative length of day and night, and 

 of other environmental factors, on growth and repro- 

 duction. Their results show that the relative length 

 of the day is a factor of the first importance in plant 

 growth, particularly with respect to sexual repro- 

 duction. The effect on sexual reproduction of en- 

 vironmental factors such as temperature, water-supply, 

 etc., seems to be simply one of acceleration or retarda- 

 tion so long as these factors are within a normal 

 range. The seasonal length of day, however, may 

 actually initiate the reproductive processes or inhibit 

 them, according as to whether the given length of 

 day is favourable or unfavourable for the particular 

 species. If the length of day is unfavourable to sexual 

 reproduction, but favourable to growth, then vegeta- 

 tive development is continued indefinitely ; but if the 

 length of day^ is favourable to both reproduction and 

 growth, then the period of sexual reproduction is 

 extended. The seasonal range in the length of day 

 is therefore an important factor in plant distribution, 

 and, moreover, the relation between length of day and 

 reproduction emphasises the great necessity for 

 seeding crops at the proper time. 



In Publication No. 295 of the Carnegie Institution 

 of Washington, entitled "A New Type of Hereditary 

 Brachyphalangy in Man," Messrs. Otto L. Mohr and 

 Chr. Wriedt illustrate the heritability of a trivial 

 character for six generations. The character is a 

 symmetrical shortening of the second joint of the 

 second fingers and toes which recurred without any 

 break for six generations within a Norwegian family, 

 some members of which emigrated to America. With- 

 out exception the peculiarity was restricted to the 

 particular phalanx mentioned, the hands and feet 

 being in other respects quite normal. There was no 

 associated shortness of stature. The anomaly mani- 

 fests itself under two distinctly different somatic 

 types, one "slightly" shortened and generally over- 

 looked by the affected individuals, the other " much " 

 shortened and very striking. No case of an inter- 

 mediate condition was observed. The brachyphalangy is 

 inherited as a dominant, not as a sex-linked, character. 

 The numerical ratio between the affected and un- 

 affected individuals in the offspring of brachy- 

 phalangous members of the family is in accordance 

 with the theoretical Mendelian expectation. All the 

 brachyphalangous individuals are heterozygous for the 

 gene in question, with one possible exception. The 

 material includes a case of identical twins, both 

 showing the same type of brachyphalangy. A genetic 

 explanation of the occurrence of the "slightly" 

 shortened and the " much " shortened types is sug- 

 gested. The authors are to be congratulated on their 

 careful working out of an interesting case. 



NO. 2641, VOL. 105] 



On Friday, June 4, the Association of Economic 

 Biologists and the Imperial Entomological Conference 

 held a joint meeting at the Rothamsted Experimental 

 Station, Harpenden. Ihe greater part of the day was 

 devoted to an examination of the field experiments 

 which were demonstrated by Dr. E. J. Russell and 

 Dr. Winifred E. Brenchley. The park grass plots 

 hrivc been under grass for some centuries ; it is not 

 known that seed has ever been sown, and at the 

 beginning of the experiments (1856) the herbage on 

 all the plots was apparently uniform. The twenty- 

 three plots are each manured differently, the same 

 treatment being maintained year after year, and the 

 southern half of each plot is limed. The difference in 

 the vegetation on the several plots is now most 

 remarkable, and, quite apart from the great and im- 

 mediate practical value of the experiments, they are 

 an ecological demonstration of the very first import- 

 ance. The Broadbalk wheat field is perhaps the most 

 famous single field in the world. Here wheat has 

 been grown continuously since 1843, the eighteen plots 

 receiving different manurial treatment which has been 

 maintained year after year. The knowledge already 

 yielded by Broadbalk has served almost to revolu- 

 tionise the earlier ideas concerning the growth and 

 needs of the wheat-plant and the nature of the soil, 

 and the attention now being concentrated upon it by 

 physicist, chemist, statistician, protozoologist, entomo- 

 logist, mycologist, and algologist should continue the 

 good work begun by Lawes and Gilbert, and so ablv 

 sustained by Sir Daniel Hall and the present director. 

 After tea Dr. A. D. Imms opened a discussion on 

 "Tropisms," giving a brief account of his own inves- 

 tigations on chemotrcpism, and relating these to the 

 general theory of tropisms formulated by Loeb. A 

 paper specially contributed by the latter author was 

 read, and Dr. Tillyard, of New Zealand, Mr. E. E. 

 Green, Dr. Williams, Sir J. C. Bose, Mr. W. B. 

 Brierley, and Prof. Neilson Jones took part in the 

 discussion that followed. 



An interesting case of extreme differentiation of 

 types of igneous rock, in which the whole series is 

 accounted for by gravitational separation, is described 

 concisely by Mr. H. C. Cooke in "The Gabbros of 

 East Sooke " (Canada Geol. Survey, Museum Bull. 

 No. 30, 1919). In view of the use of the mineral 

 name " anorthose " for soda-microcline, objection may 

 be taken to the term " anorthosite " for rocks with 

 felspar akin to anorthite. 



Prof. G. CesAro sends us a paper on minerals 

 from Monte Somma and Vesuvius, which is of interest 

 as having been prepared for issue in the Bulletin 

 de la Classe des Sciences of the Academic royale de 

 Belgique in 1914, and actually circulated by its author 

 in 19 19. Prof. Cesaro has meanwhile, by the stress 

 of war, become personally known to a circle of British 

 mineralogists, who will maintain cordial relations 

 with him despite his return to his own country. As 

 an appendix to the paper Prof. Cesaro describes an 

 apatite from Cornwall as having a low birefringence, 

 and therefore a high fluorine content, and in dealing 

 with similar apatite from Vesuvius he quotes from 

 his previous work the relations between the fluorine 

 present and certain angles of the crystals. 



