no 



SCIENCE. 



[N. S. Vol. XIX. No. 472. 



considerable) how difficult it is, otherwise, to 

 avoid the occasions of personal disputes, or 

 reflections; which, for my part, I heartily de- 

 sire to shun" (Vol. v., p. 252b). 



One can not but conclude, judging from the 

 phraseology, that the passage in the Phil. 

 Trans, cited by Dr. Bolton is from the same 

 pen as Henry Oldenburg's prefatory note. 

 Further evidence of the same authorship is 

 found in the capitalization, following, as it 

 does, the German method. Now Eobert Boyle 

 would not be likely to use this mode of writing, 

 while Henry Oldenburg, being a native of 

 Bremen in lower Saxony, might easily have 

 lapsed into the style of his native tongue. 



John C. Shedd. 



Physicai, Laboratory, 

 CoLOKADO College. 



SPECIAL ARTICLES. 

 COLOR INHERITAiSrCE IN MICE. 



Within the last few years great interest has 

 been aroused by the rediscovery of Mendel's 

 Law of Dichotomy in plant hybridization. 

 This law has been confirmed for many species 

 of plants, especially by De Vries (1902, pp. 

 146-151, etc.), Correns, Tschermak and others. 

 The study of mice, rats and rabbits has yielded 

 a partial confirmation of this law for animals. 

 I wish here to contribute additional although 

 too meager data drawn from my experiments 

 of the past four years. 



The two great laws enunciated by Mendel 

 were these: Of the two antagonistic peculiari- 

 ties possessed by two races that are crossed, 

 the hybrid, or mongrel, exhibits only one ; and 

 it exhibits it completely, so that the mongrel 

 is not distinguishable as regards this character 

 from one of the parents. Intermediate con- 

 ditions do not occur. That one of the two 

 parental qualities that alone appears in the 

 mongrels is called dominant; the other reces- 

 sive. Second, in the formation of the pollen 

 or egg-cell the two antagonistic peculiarities 

 are segregated; so that each ripe germ cell 

 carries either one or the other of these pe- 

 culiarities, but not both. It is a result of the 

 second law that in the second generation of 

 mongrels each of the two qualities of their 

 grandparents shall crop out on distinct indi- 



viduals, and that the recessive quality shall 

 appear in 25 per cent, of the individuals, the 

 remaining 75 per cent, having the dominant 

 quality. Such recessive individuals, crossed 

 inter se, should never produce anything but 

 recessive offspring. 



Now experiments with animals have re- . 

 vealed the existence of recessive qualities — 

 e. g., in mice, when white and wild gray are 

 crossed and the mongrel offspring are crossed 

 inter se, the second mongrel generation will 

 yield some white mice, and such white mice, 

 bred inter se, will thenceforth produce only 

 white mice. These results have been got by 

 Crampe (1885), von Guaita (1898, 1900)— 

 cf. Davenport (1900)— Cuenot (1902, 1903) 

 — cf. Bateson (1902, p. 173)— Darbishire 

 (1902, 1903), Castle (1903) and Bateson 

 (1903). Is the percentage of the recessive in- 

 dividuals always 25 ? In such a second mon- 

 grel generation Cuenot (1902) found 162 gray 

 and 57 albino individuals, or 74 per cent, to 

 26 per cent., and in von Guaita's breedings 

 between walzing and albino mice the crossed 

 gray hybrids gave 25 per cent, albinos; results 

 that accord with theory. But instead of the 

 75 per cent, gray which Mendel's law calls for, 

 von Guaita got 57 per cent, gray and 18 per 

 cent, walzing mice of gray, gray-white, black, 

 and black and white colors. Rabbits gave 

 Woods (1903) only 21 per cent, instead of 

 25 per cent, of the recessive type in the second 

 mongrel generation, and in crossing hybrids 

 with albinos he got only 40 per cent, albinos 

 instead of 50 per cent., as theory demands. 



The discussion concerning the validity of 

 Mendelism for mice has been based chiefly 

 upon crosses between albinic mice on the one 

 hand (Crampe, Cuenot, Castle and Allen) 

 and gray or walzing mice on' the other 

 (Haacke, von Guaita, Darbishire). Bateson 

 (1903) alone has recorded, without details, the 

 results of crossing mice of varied colors. 

 His data will be referred to in the following 

 account of my experiments. 



A. THE offspring OF MICE OF THE SAME COLOR. 



I. Albino "}(_ Albino. — This cross appears to 

 produce only albinos. Bateson (1903, p. 76) 

 has examined the evidence and finds only one 



