No. 2, September, 1920] GENETICS 209 



very small pair of chromosomes, and five known groups of linked genes. Author points out 

 that only twenty-seven mutant characters, of which fourteen are sex-linked, have thus far 

 been investigated in this species, and thai the failure to delect the sixth (and presumably 

 small) group, is not surprising in view of the small number of characters investigated. He 

 promises full data on this case in a future publication.— Jo An S. Dexter. 



1683. MiTsciiKiu.H n, EiLH, Alfred, tiber kiinstliche Wunderiihrenbildung. [The arti- 

 ficial production of abnormal heads of cereals.) Zeitschr. Pflanzenziicht. 7: 101-109. 8 fin. 

 Dec, 1910. 



1584. Moiih, Otto L., and Chr. Wriedt. A new type of hereditary biachyphalangy in 

 man. Carnegie Inst. Washington Publ. No. 295. 64 p., 7 pi., 4 fig- 1919. — A careful study 

 based on personal examinations, authentic records, photographs and X-ray plates has been 

 made of the hands of nearly 100 members of a Norwegian family in which an unusually clear- 

 cut type of brachyphalangy occurs in at least six generations. The trait behaves as a sirn 

 dominant and is not sex-linked. In heterozygous individuals the manifestation is confined 

 exclusively, so far as can be determined, to the middle phalanx of the index finger (and the com- 

 parable phalanx of the corresponding toe). The affected phalanx may be shortened to a 

 moderate degree or reduced almost to the point of elimination in which case it is sometimes 

 subluxated toward the ulnar side causing the terminal phalanx to bend radial-ward giving a 

 "crooked" finger which is not (in this family) genetically different from a "short" finger. Of 

 especial interest is the fact that the manifestations of the trait do not fluctuate around a 

 single mode but arrange themselves in two distinct groups without any overlapping. The 

 authors, therefore, postulate a second, modif3 r ing, gene which intensifies the effect of the main 

 gene. This modifier is one of presumably manj' such genes which may be widely distributed 

 in the human germ plasm without often having an opportunity to manifest themselves. 

 Certain individuals who have married into the family have been heterozygous for the modi- 

 fier, others have lacked it altogether. Failure to recognize the existence of this gene might 

 easily have led to erroneous conclusion as to "dilution" of the main gene. In reality no dilution 

 has taken place in the course of six generations. Of possibly great importance is the result of the 

 marriage of two affected individuals. A single marriage of this sort yielded three children, 

 one of whom lacked all fingers and toes and died at the age of a year. The authors are inclined 

 to regard this case as the one instance of an individual homozygous for brachyphalangy 



to look upon the gene as one which, when heterozygous, produces relatively inconsequential 

 effects, but which when homozygous produces very serious, perhaps lethal, results. — C. II . 

 Danforth. 



1585. Mohr, Otto L. Mikroskopische Untersuchungen zu Experimenten iiber den Ein- 

 fluss der Radiumstrahlen und der Kaltewirkung auf die Chromatinreifung und das Hetero- 

 chromosom bei Decticus verruccivorus (o 71 ). [Microscopic studies in experiments on the 

 influence of radium rays and effect of cold on the maturation and the heterochromosome of 

 Decticus verruccivorus (&).] Arch, mikrosk. Anat. 92: 300-388. 6 pi. 1919. 



1580. Morgan, T. H. Variations in the secondary sexual characters of the fiddler crab. 

 Amer. Nat. 54 : 220 2 !0. 6 fig. May-June, 1920. — Two variations are described that are shown 

 not to be due to regeneration. Whether due to genetic change, to infection, or to some em- 

 bryonic "slip" could not be determined. Literature relating to sex-intergrades in Crustacea 

 is reviewed.— 7'. //. Morgan. 



1587. Mottet, S. Digitalie hybride de Lutz. [The Lutz Digitalis hybrid.) Rev. Hortic 

 91: 390-397. 1919.— See Bot. Absts. 5, Entry 1827. 



1588. Mumford, H. W\ Famous Angus cows of Scotland. Breeder's Gaz. 76: 462-463. 

 1919. — Author discusses briefly the records of the foundation cows of certain famous families 

 of the Aberdeen Angus breed. — Sewall Wright. 



