No. 1, November, 1921] 



GENETICS 



19 



103. Lenz, F. Kann eine quantitative Fluktuation von Erbfactoren von wesentlicher 

 Bedeutung fiir Artbildung sein? [Can a quantitative fluctuation of genes be of significance 

 for species formation?] Zeitschr. Indukt. Abstamm.- u. Vererb. 25: 169-175. 1921. — This 

 paper consists of a critical discussion of Goldschmidt's theory that evolution proceeds 

 mainly through the accumulation of fluctuations in the genes, rather than through mutation 

 and the recombination of genes. The theory goes further, explaining that genes are purely 

 chemical in nature, each one being an enzyme, whose quantitative fluctuations are expressed 

 in the soma. The obvious difficulties for such a chemical theory are indicated: In order to 

 explain any stability or continuity in a sea of fluctuations, it becomes necessary to assume 

 some limiting structure which then becomes the controlling basis of the continuity as well 

 as of the fluctuations. This is shown to be the case when Goldschmidt assumes the chromo- 

 somes to be colloidal skeletons which absorb the inheritance-enzymes at cell division, and form 

 the mechanism for their equal division between the daughter cells. Aside from this difficulty, 

 Goldschmidt's theory offers no explanation for the development of new genes (enzymes). 

 Further difficulties are mentioned, such as the failure to distinguish between inherited varia- 

 tions and those that are only somatic; and objections are made to various specific statements 

 of Goldschmidt.— £. C. MacDowell. 



104. Little, C. C., and M. Gibbons. Evidence for sex-linked lethal factors in man. 

 Proc. Soc. Exp. Biol. Med. 18: 111-11.5. 1921. — After illustrating the inheritance of the lethal 

 factor in yellow mice and sex-linked inheritance in the tortoise-shell cat, the authors show 

 the manner of inheritance of haemophilia and color blindness in the human race. They then 

 demonstrate that any sex-linked lethal factors in man would follow the same line of inheritance, 

 and examine the data of Bulloch and Fildes on haemophilia as well as the data of the Eu- 

 genics Record Office. If sex-linked lethal factors are linked to the allelomorph for normal in 

 the case of haemophilia and color blindness each, there should be an excess of abnormal types 

 among the males as compared with the normal types, and there should also be a decreased 

 proportion of females in families having no excess of affected males. The following table 

 shows the results: 



The excess of haemophilics is so great as compared to the number expected that the odds 

 exceed 1 to a billion that chance is the cause. Similarly, the odds that the excess in the case 

 of color blindness is due to chance are 20 to 1. In the case of deficiency in the females, the 

 odds are 1 to 2 billion in the case of haemophilia and 1 to over 500 in the case of color blind- 

 ness. — Edward iV. Wentworth. 



105. LoNNBERG, EiNAR. Hybrid gulls. Arkiv Zool. 12: 1-22. 3 pi., 6 fig. 1919.— A 

 number of hybrids from (1) Larus leucopterus 9 X L.fuscus d^ and (2) L. glaucus 9 X L. 

 marinus cf are described in detail ; many of these birds were bred in confinement. The pinkish 

 feet of (9 ) leucopterus were dominant over yellow feet of (cT) fuscus; black pigment in the 

 primaries of fuscus is dominant over absence of the corresponding pigment of leucopterus. 

 The white on the primaries was variable in the hybrids. The parent species are believed to 

 represent extreme stages of development in opposite directions; the hybrid is intermediate, 

 and is interpreted as more primitive or generalized, — in other words, it is considered "a rever- 

 sion to an ancestral form." — The hybrid between L. marinus and L. glaucus is taken to be 



