274 EXPEEIMENT STATION RECORD. 



Meudolists is not the law of dDiaiuance but an insntHeieut consideration of the 

 iuflnence of environment npon the developing organism. The rnle of dominance 

 tends to lower the correlation between offspring and ancestor, while food, climate, 

 exposure to disease, and other environmental factors tend to increase the ances- 

 tral correlation in the study of characters such as growth and body size, and 

 may even outweigh the oiiposite tendency of the law of dominance if they are 

 not excluded. Mathematical formulas are used to demonstrate these and other 

 arguments of the author on ancestral correlation. 



The effect of selection upon Mendelian characters manifested in one sex 

 only, ^y. E. Castle {Jour. Expt. ZooL, 8 {I'JIO), No. 2, pp. iS5-i. 92). —The 

 author discusses the criteria by which Mendelian inheritance can be distin- 

 guished from non-^Iendelian. Applying these criteria to results obtained in 

 experiments with silk moths, univoltinism is deemed to be a Mendelian dominant 

 to bivoltinism. although Miss McCracken (see page 2G0) views these characters 

 as non-Mendelian. 



Inheritance of the color of the seed coat of maize is used to illustrate the 

 persistency of ^Mendelian character when manifested only in the female line, 

 even when repeatedly excluded by selection, making it unnecessary to assume a 

 •'mysterious pull of ancestry," "delayed conjugation," or other hypothesis. 



Atavism, M. IIilzheimeb (Ztschr. Induktivc Ahstain. it. VcrcrhuniiHlchrc. 3 

 {Id 10), Xo. 3. pp. 20 1-21. 'i, fiffs. -'i). — The author thinks that the poll character 

 in cattle is a mutation and not a reversion, because no fossil hornless ancestor 

 of the ox has yet been found, and because the poll character appears also in the 

 yak, buffalo, sheep, and goat. It is improbable that all of these species had 

 hornless ancestors and that horns should have developed in the same manner 

 in all cases. In a discussion of atavisim, or reversion, it is stated that true 

 reversion occurs in pigeons, mice, rabbits, guinea pigs, and other animals hav- 

 ing a monophyletic origin, but seldom in dogs, goats, sheep, cattle, and others 

 of a polyphyletic origin. 



[A note on hybrid ducks] {I'roc. Zool. Soc. London, IDO'J, III. pp. 698, 

 599). — A hybrid obtained by crossing 4 different species of ducks was to all 

 outward appearances indistinguishable from the pure-bred wild mallard, a 

 striking example of the truth of Mendel's law. Hybrids obtained from 5 differ- 

 ent species proved fertile up to the fourth generation, since the last cross with 

 a pure species. 



Contributions to the study of the Equidse. I, The differentiation of the 

 three species of zebras. II, On hitherto unrecorded specimens of Equus 

 quagga. Ill, On a portion of a fossil jaw of one of the Equidte, W. Kiuge- 

 WAY {I'roc. Zoo/. .S'oc. London, I'JO'.K HI, pp. 5-'/ 7—588, jigs. '/i). — A number of 

 skins of zebras and quaggas are illustrated and described. The author con- 

 cludes that the same species may vary in coloration according to the locality, 

 and that apparently the quaggas of Orange River and Cape Colony were not 

 specifically different from the Burchelline zebras. A fossil jaw from the late 

 tertiary deposits of East Africa is apparently a new species, Equus holUsi, and 

 an ancestor of one of the zebras. 



Ag'es of sires and speed transmission, P. 1. Mixer {Breeder's Gaz., 57 

 {IDIO), yo. n, p. 10.30, chart 1). — The author presents a table and chart which 

 show the frequency distribution of over 1,300 individuals, the get of IS sires, 

 tabulated with respect to age of sire and the speed of the offspring. 



Three individuals which made a record of 2 :14 and 3 which made a record of 

 2:30 were foaled when the siri-s were 3 years old. Twelve-year old stallions 

 producetl progeny from 2 :30 down to 2 :0G. The 2 :18 records were made by 

 offspring produced by sires of all ages, from 3 up to at least 25 years. The 

 mean si)eed of the get varied but little, being with the 3-year old stallions 



