EXAMPLE. OF THE MLNDE.L LAW. 21 



really crossbreds, though like the crossbreds raised by crossing the two original yarieties, they, 

 only exhibit the dominant character. 



" To resume, then, it was found that by self-fertilizing the original crossbreds the same pro- 

 portion was always approached, namely, 25 dominants, 50 crossbreds, 25 recessives. * * * 



' Like the pure recessives, the pure dominants are thenceforth pure, and only give rise to 

 dominants in all succeeding generations studied. 



" On the contrary, the 50 crossbreds, as stated above, have mixed offspring. But these 

 offspring, again, in their numerical proportions, follow the same law, namely, that there are 

 three dominants to one recessive. The recessives are pure like those of the last generation, but 

 the dominants can by further self-fertilization and examination or cultivation of the seeds pro- 

 duced, be again shown to be made up of pure dominants and crossbreds in the same proportion 

 of one dominant to two crossbreds." 



In illustrating the application of Mendel's law, Prof. T. H. Morgan, in an article on " The 

 Determination of Sex," in the Popular Science Monthly, for Dec., 1903, makes this example: 

 " If a white mouse is crossed with a wild gray mouse all the offspring of this cross will be gray 

 like the wild mouse. The gray color of the gray mouse is said to be dominant, and the white 

 color (inherited from the other parent) does not appear, but is supposed to be present in a sort 

 of latent condition. It is said to be recessive. If now these primary hybrid mice are inter- 

 bred, some of their young will be white, and the rest gray in the proportion of one to three. 

 If these white mice, when they become grown, are interbred, their offspring will always be 

 white as well as all their subsequent descendants. Some of the gray mice will also breed true, 

 but the rest that are gray hybrids will, if interbred, give rise to some white and some gray In 

 the proportion again of one to three." 



We do not understand that in this illustration Prof. Morgan assumes to state facts about the 

 crossing of white and gray mice. We take it that the case is an assumed one, except perhaps 

 as to the statement that the progeny of the first cross would be all gray. 



Xow it is a question which some poultrymen may be able to answer partly from past 

 experience in breeding, whether Mendel's law will apply to any characters in poultry, and if 

 so, to how many and to what characters. Tba writer has made a good many crosses, observ- 

 ing results chiefly with reference to the laying and table qualities of the stock produced, but in 

 connection with these things has taken casual notice of other points which might be supposed 

 to come un-der the operation of the Mendel law if that applies. (Bateson takes pains to 

 emphasize and to reiterate that the law does not appear to be of universal application). We 

 have observed some results, for instance, with regard to color or some other character which 

 suggested that Mendel's law might apply in some cases matings of certain individuals and 

 might not apply in similar cases in which different individuals were used. For instance, we 

 once made a cross of White Leghorn on Light Brahma in which all the progeny were white, 

 the color of the Leghorn sire. We have had other crosses in which the colors of the females 

 of the male's line were approximately reproduced in his female offspring, while the male 

 offspring resembled the color of males of the variety of their dams. Again we have had both 

 males and females, without exception, of color type intermediate between the variety colors of 

 sire and dam, and also intermediate in size, in shape, in size of comb, in size of tail, etc. 



But these were not crosses of varieties. They were crosses of breeds. To reproduce 

 Mendel's experiments with reference to color of fowls we must take two varieties differing only 

 In color, as, say, the Black and the White Wyandotte, Leghorn, Hamburg, Cochin, Laugshan, 

 or Minorca. While we cannot at present refer to a record of such across, our impression is 

 that cases which would seem to confirm the Mendel law are extremely rare. The variety of 

 results we have seen in color, considered in connection with the limited range of Mendel's 

 experiments, suggests that though he simplified his statement by the introduction of the terms 

 " dominant " and " recessive," the introduction of those new terms made the relations of his 

 observations to certain older principles obscure. Bateson calls attention to the use of the terms 

 "dominant" and " recessive" as a clever avoidance of "the complications involved by the use 

 of the expression * prepotent,' " but it seems to us that by ignoring " prepotence" the facts are 

 placed on a false basis, for it is not possible that the law may be found to apply to the 

 phenomena of prepotency rather than to heredity in general. Bateson approaches, but does 



