GENETICS. 13 
It has been found possible to determine the linear order of the genes 
within any one chromosome pair and to obtain a measure of their 
distance apart. On the basis of this information, when the position 
of a new gene has been determined with respect to any two others in 
its group, it is possible to predict accurately the relations that it will 
show to any other genes. For the methods used in these analyses, 
and for numerous other special developments of the subject, the 
reader is referred to the following publications: 
BRiEF ACCOUNTS: 
Wison, E. B. 1913. Heredity and microscopical research. (Leidy lecture.) Sci- 
ence, n. s., 37: 814-826. 
. 1914. The bearing of cytological research on heredity. (Croonian lecture.) 
Proc. Roy. Soc. B, 88: 333-352. 
Moraan, T. H. 1915. The constitution of the hereditary material. Proc. Amer. 
Phil. Soc., 54: 143-153. 
. 1915. Localization of the hereditary material in the germ cells. Proc. Nat. 
Acad. Sci., 1: 420-429. 
and C. B. Bringes. 1916. (Introductory portion of) Sex-linked inheritance 
in Drosophila. Carnegie Inst. Wash. Pub. No. 237, 87 pp., 2 plates. 
NacutsHem, H. 1919. Die Analyse der Erbfaktoren bei Drosophila und deren 
zytologische Grundlage. Zeits. ind. Abst. Vererb., 20: 118-156. 
FULL TREATMENTS: 
Morgaan, T. H. 1916. A critique of the theory of evolution. Princeton. 197 
+ x pp. 
. 1919. The physical basis of heredity. 305 pp. Philadelphia. 
, A. H. Sturtevant, H. J. Muuusr, and C. B. Brings. 1915. The mechan- 
ism of Mendelian heredity. 262 + xiii pp. New York. 
Bascock, E. B., and R. E. Cuausen. 1918. Genetics in relation to agriculture. 
675 + xx pp. New York. 
DESCRIPTIONS OF MUTANTS: 
Moraan and Brinces. 1916. (See above.) 
Bringss, C. B., and T. H. Moraan. 1919. The second chromosome group of mutant 
characters. Carnegie Inst. Wash. Pub. No. 278, pp. 123-304, 7 plates. 





MUTATIONS IN SPECIES OTHER THAN D. MELANOGASTER. 
Several other species of Drosophila have been examined for muta- 
tions, though none so extensively as D. melanogaster. There is now 
convincing evidence that mutations occur with something like the 
same frequency in these species; that the mutants are of the same 
general nature; that in some cases the same identical mutation has 
occurred in different species; and that the genetic behavior of these 
other species is in general very similar to that of D. melanogaster. 
There follows an abstract of the available data on these species, 
arranged alphabetically : 
D. affinis: Hyde (1915) has reported a “jaunty” wing, inherited as a non- 
sex-linked recessive. He used the name “‘confusa”’ for this species, 
which was at that time undescribed. 
D. busckit: Warren (1917) found two eye-colors, both recessive and not 
sex-linked, but apparently lying in the same chromosome. 
D. caribbea: I found a curved wing that was a non-sex-linked recessive 
(unpublished data). 
