326 GENETICS [Bot. Absts. 



maries of a few family history studies. It insists that physicians must not give eugenical 

 advice without adequate family history data, and urges that parents should not be sensitive 

 in the matter of taking stock of the mental limitations of their children, and finally advises 

 that education, co-operation and the setting forth of principles and the extablishment of 

 custom are better than legislation in promoting eugenical ends. — H. H. Laughlin. 



2173. Miyake, K., and Y. Imai. Digitalis no Kwasyoku oyobi sonotano Keisitu no Iden 

 ni tuite. [On the inheritance of flower-color and other characters in Digitalis purpurea.] 

 [Japanese.] Bot. Mag. Tokyo 33 (Japanese part): 175-186. 1919.— Experiments were per- 

 formed on natural hybrids. The fact first discovered by Miss Saunders that glabrousness is 

 dominant to hairiness and that the segregation of these allelomorphs takes place in 3: 1 ratio 

 was confirmed. Purpleness of stems, peduncles, etc., were found to be dominant to their 

 greenness; their segregation takes place in 3: 1 ratio. Self-fertilization of purple flower has 

 given rise to 23 purple-flowered and 7 white-flowered plants, whence authors think that white 

 is recessive to purple and not dominant, as it should be according to Keeble, Pellew and 

 Jones (New Phytologist 9,1910). Authors consider that two factors C and P with their 

 absences c and p are concerned in the production of flower-color, P making flowers purple in 

 the presence of C. — S. Ikeno. 



2174. Mohr, Otto L. Character changes caused by mutation of an entire region of a chro- 

 mosome in Drosophila. Genetics 4:275-282. May, 1919. — The appearance of notch wing 

 (for the eighth time) was due to mutation or "deficiency" of an entire region of the sex 

 chromosome about 4.8 units long and including many genes. Like bar-deficiency, notch allows 

 the allelomorphic genes, even though normally recessive, to show when in heterozygous con- 

 dition. Like bar-deficiency, it is lethal in males. Unlike bar-deficiency, notch exaggerates 

 the effect of allelomorphic genes. Notch cannot therefore be mere loss or inactivation of 

 genes, since no exaggerating effect is produced in XO males, where one sex chromosome is 

 known to be entirely missing. No crossing over occurs within the "deficient" notch region; 

 and crossing over is disturbed in neighboring regions. — Alexander Weinstein. 



2175. Mohr, O. L., and A. H. Sturtevant. A semi-lethal in Drosophila funebris, that 

 causes an excess of males. Proc. Soc. Exp. Biol. Med. 16: 95-96. 1919. — In D. melanogasler, 

 deficiency of females, opposite to effect of sex-linked lethals, is much less frequent and hith- 

 erto unexplained. In a race of D. funebris, ratios vary from all males to approximate equality. 

 Data indicate excessive sex-limited mutation causing abnormal abdomen, which commonly 

 affects only females, though transmitted by both sexes. Degree of abnormality is dependent 

 on environmental conditions, as yet uncontrollable. Very abnormal females die as pupae, 

 and excess of males results. — C. R. Plunkett. 



2176. Morgan, T. H., and C. B. Bridges. The construction of chromosome maps. 

 Proc. Soc. Exp. Biol. Med. 16:96-97. 1919.— Accuracy of chromosome map depends upon 

 (1) mutants and wild-type cleanly separable and equally viable; (2) loci properly spaced; 

 (3) correction for double crossing over; (4) uniform conditions, especially of age, temperature, 

 and crossing-over modifiers; (5) any experiment figured only once for each region of chromo- 

 some; (6) data adequate and (7) properly weighted; (8) framework of map constructed from 

 most significant loci, others interpolated as accurately as possible. — C. R. Plunkett. 



2177. Nachtsheim, Hans. Die Analyse der Erbfaktoren bei Drosophila und deren zyto- 

 logische Grundlage. [Analysis of the inheritance-factors in Drosophila and their cytological 

 basis.] Zeitschr. indukt. Abstamm. Vererb. 20: 118-156. 12 fig. Jan., 1919. — An exhaus- 

 tive and accurate review of the literature on the genetics and cytology of Drosophila, includ- 

 ing nearly all papers published up to the end of 1915. — A. H. Sturtevant. 



2178. Neethling, J. H. A preliminary note on dwarfs appearing in Gluyas Early (wheat) 

 hybrids. South African Jour. Sci. 14: 540-547. 6 fig. 1918. — Certain crosses between Gluyas 

 Early and other common wheats produced a number of dwarf forms in the F 2 and F 3 . The 



