^New Yokk Agricultural Experiment Station. 467 



its hereditary characters in the same state — a given character 

 is permanently either homozygous or heterozygous. Therefore, 

 the results obtained in these crosses are to be expected whenever 

 the same varieties are crossed. Hence the F2 generation is not 

 so necessary in breeding apples as with plants grown from seed. 



The reader must keep in mind, however, that there may be 

 several explanations of the behavior of characters in the first 

 generation following a cross and that the crucial test of what- 

 ever hypotheses are set forth as regards the characters in these 

 hybrid apples is the behavior in the subsequent generations. 

 Attention must be called, too, though scarcely necessary to one 

 having knowledge of even the rudiments of genetics, to several 

 sources of error in this experiment. Thus, the number of hybrid 

 offspring of these crosses is so small that it is not probable that 

 all of the possible combinations of the diiferent kinds of germ 

 cells are to be found even in the crosses having the largest pro- 

 genies. Again, the work is vitiated somewhat by the fact that 

 the total progenies of the several crosses have not been under 

 (observation, 23 out of 148 or about 15 per cent of the total num- 

 ber, having succumbed to the accidents which befall seedling 

 plants, there being, however, no selection by the hand of man. 

 Lastly, we are working with material of unknown parentage. 



The characters of the apple chosen for consideration are those 

 most important to apple growers ; namely, color of skin, color of 

 flesh, shape, size and acidity. 



Color of skin. — The colors of apples may be roughly divided 

 into five classes; yellow, yellow with a light red blush, yellow 

 with one-third to one-half its surface overlaid with red, nearly 

 solid red, and reddish black. The apples in these crosses con- 

 tain only three colors, yellow, red and the intermediates between 

 these. Whether the distribution of the intensity of color depends 

 upon a complex or a simplex of unit characters, is at present 

 impossible to determine. Unknown factors play too large a part 

 to permit of an easy determination. Thus, we do not know 

 exactly the nature of color; the amount of color in a variety de- 

 pends largely upon the soil and the method of orchard manage- 

 ment ; and, we are working with material of unknown parentage. 

 But if we can state roughly how the color is inherited in a few 



