418 



SCIENCE 



[N. S. Vol. LI. No. 1321 



very small- — and should, therefore, according 

 to the chromosome theory, have six linkage 

 groups, one of which might be expected to con- 

 tain relatively few genes. From present evi- 

 dence it seems probable that the five linkage 

 groups, thus far detected, represent the five 

 large pairs of chromosomes. Detection of the 

 sixth group, representing the very small pair, 

 would hardly be expected until a larger num- 

 ber of mutants had been obtained. 



The data upon w'hich these conclusions are 

 based will be published in detail elsewhere, but 

 may be summarized as follows : 



Fourteen of the 27 characters are aex-linked, 

 forming Group I. The remaining (non-sex- 

 linked) characters fall into four groups — 

 Group II. with three characters. Group III. 

 with four characters, Group IV. with three 

 characters and Group V. with three characters. 

 I Maps of the five groups, based on crossover 

 values, as determined thus far, are respectively 

 .about 90, 40, 60, and 20 units long. These 

 lengths are based, respectively, on data involv- 

 ing 12, 2, 4, 3, and 2 "loci," and hence will 

 proibably be extended considerably when more 

 characters are studied. Although the values 

 are only approximations, ibecause of the small 

 number of genes involved, they show that a 

 relatively large amount of crossing over occurs 

 jn some of the groups. In the fourth group 

 the three genes api)ear to be completely linked, 

 but since there is no other evidence to indi- 

 cate that they are allelomorphs they are as- 

 sumed, tentatively, to represent three different 

 loci. 



Owing to the fact that in D. virilis, as in D. 

 melanogaster, there is no indication of crossing 

 over in the male, it has been possible to secure 

 clear-cut evidence of the distinctness of the 

 linkage groups, because back-crosses of hetero- 

 zygous males always give complete linkage, if 

 the genes belong to the same group, or free 

 segregation if they do not. Thus representa- 

 tives of each group (exclusive of the sex-linked 

 group) have been t«!St«d with representatives 

 p{ every other group and found to give free 

 segregation, whereas with members of their 



2 See Metz, C. W., Amer. Nat., Vol. L., pp. 587- 

 599, October, 1916. 



own groups they gave complete linkage. The 

 crossover values were, of course, obtained by 

 back-crossing females instead of males. 

 , It should be noted that in the case of the 

 fourth group no crossing over has yet been de- . 

 tected in either sex, but only three characters 

 have been studied in this group, and there can 

 be little doubt that the sexual difference, as re- 

 gard's crossing over, will prove to be the same 

 here as in the other groups. 



Chas. "W. Metz 

 Station tor Experimental Evolution, 

 Cabnkgik Institution op Washington 



THE AMERICAN ASSOCIATION FOR 

 THE ADVANCEMENT OF SCIENCE 



SECTION H— ANTHROPOLOGY AND 

 PSYCHOLOGY 



At the St. Louis meeting of the American Asso- 

 ciation for the Advancement of Science, Section 

 H presented a two-day program. The Monday 

 morning program was given over to papers of 

 especial anthropological interest. Unfortunately 

 due to conflict in the announcements few were 

 present and the session was postponed, resulting 

 in only a few papers being given. On Tuesday 

 morning the Section united with Section L — Edu- 

 cation — in a joint program. The address of the re- 

 tiring chairman of the Section, Dr. Ales Hrdlieka, 

 was entitled "The relations of anthropology and 

 psychology. ' ' 



Due to action of the Council of the Association 

 the old Section H — Anthropology and Psychology 

 — ^has been divided up into new sections. The now 

 Section H will be restricted to anthropology and 

 the new Section I to psychology. Officers for both 

 Sections were elected on Tuesday afternoon. 



The officers for Section H — Anthropology — are: 

 Vice-president of the Association and chairman of 

 the Section, Dr. G. B. Gordon, University Museum, 

 PhUaddlphia, Pa.; Secretary, Dr. E. Hooton, Pea- 

 body Museum, Cambridge, Mass.; Members of Seo 

 tiondl Council, Dr. F. W. Hodge, Museum of the 

 American Indian, 1 year; Professor B. J. Terry, 

 Wa^ington University, 2 years; Dr. B. Laufer, 

 Field Museum of Natural History, Chicago, 3 

 years; and Dr. Ales Hrdlitka, United States Na- 

 tional Miiseum, 4 years. 



The officers for Section I— Psychology — are: 

 Vice-president of th^e Assoddion and chairman, 

 Professor Edward K. Strong, Jr., Carnegie Insti- 

 tute of Technology; Secretary, Professor F. N. 

 Freeman, University of Chicago (for 4 years) ; 



