534 



SCIENCE 



[N. S. Vol. XXXIX. No. 1006 



known studies and was carried out with 

 Castle's own material and with his coopera- 

 tion and help. The experiments now reported 

 show that the Nilsson-Ehle explanation of 

 " blended " inheritance (i. e., two or more non- 

 allelomorphic factors producing phenotypically 

 similar phenomena) may be applied to size 

 difEerences in hybrid rabbits. 



The fact that crosses between negroes and 

 whites give mulattoes has long been pointed 

 to as proof of " blending." But, as is well 

 known, various pigments are here involved, 

 viz., black, red and yellow. Davenport^ has 

 shown clearly that the children of two mulatto 

 parents exhibit great variation in color. Oc- 

 casionally some are light enough to " pass for 

 whites " when away from home. The explana- 

 tion of this phenomenon, as based on multiple 

 factors, is suggested by Davenport. In the 

 light of MacDowell's own work and the work 

 that he cites there can be little doubt of the 

 correctness of this view. Probably there are 

 separate factors (determiners) for the several 

 pigments and more than one, perhaps many, 

 for the black pigment. 



A quotation from MacDowell's paper shows 

 the conclusions drawn from his studies of rab- 

 bits. But his statements may be applied to 

 human skin color and, no doubt, to many 

 heritable characters of human beings : 



Offspring from crosses between extremes are 

 generally of an intermediate nature. In the fol- 

 lowing generation new forms appear tliat are sim- 

 ilar to the original parents or even more extreme. 

 The greater number of individuals are intermedi- 

 ate. In certain cases crosses between similar lines, 

 after a first generation like the parents, give a 

 second generation in which a wide range of grades 

 appear. These are the facts definitely ascertained 

 from the -work that has been done. . . . The in- 

 terpretation of multiple factors can be applied to 

 all the facts. It goes hand in hand with the muta- 

 tion and pure-line doctrines of de Vries and Jo- 

 hannsen, and in its breadth of application, and 

 its comprehensive simplicity, this theory, based on 

 the assumption of the segregation of distinct 

 units, is very attractive; by its use as a working 

 hypothesis important facts have been discovered; 



2 ' ' Heredity in Relation to Eugenics, ' ' pp. 36- 

 38, New York, 1911. 



its acceptance and further development will help 

 to establish a broad and unified system of hered- 

 ity. 



Doubtless many " well-informed " persons 

 still hold to the idea of " blended " inheritance. 

 It is with the hope of calling attention to the 

 Mendelian phenomena involved that this note 

 is submitted. A careful reading of MacDow- 

 ell's article will clear up many puzzling diffi- 

 culties for those who are interested in heredity 

 but have not kept up with the literature of 

 the past few years. Francis Eamaley 



University op Colokado, 

 Boulder, Colo. 



diadophis punctata in northern wisconsin 

 EuTHVEN^ has recorded the occurrence of 

 the ring-necked snake, Diadophis punctata 

 (Linnseus), at Marquette, Michigan, on the 

 strength of specimens having " been taken by 

 Dr. Downing," but later the same authority 

 states : " The Marquette record is particularly 

 open to question and has not been recorded 

 upon the map."^ Not having seen a specimen 

 from Marquette, Ruthven was perfectly justi- 

 fied in making his later statement, in view of 

 the fact that the locality was considerably be- 

 yond the known northern geographic range of 

 the species. It may be interesting, however, 

 in this connection to note that on July 5, 1912, 

 I collected a specimen of this species near 

 Ehinelander, Oneida county, Wisconsin, a 

 locality about 120 miles west-southwest of 

 Marquette, Michigan. The snake was found, 

 one and one half hours after sunset, extended 

 full length across the wheel tracks of a sandy 

 road bordering low second-growth woods of 

 Pinus divaricata, Betula papyrifera, Populus 

 iremuloides and Quercus coccinea; in the late 

 twilight the animal was scarcely visible from 

 the wagon in which I was driving. It made 

 no resistance to being captured, was perfectly 

 docile, and soon became tame. It showed a 

 tendency towards positive reaction to contact 



1 Euthven, A. G., 1906, Eeport Geol. Surv. 

 Michigan for 1905, p. 111. 



2 Euthven, A. G., Thompson, C. and Thompson, 

 H., 1912, "The Herpetology of Michigan," 

 Michigan Geol. and Biol. Surv., publ. 10, p. 107. 



