150 



THE AMEBICAN NATURALIST 



[Vol. LI 



TABLE I 



NO Blue x Blue in the Blue Andaluslaji 



nection, however, we can not pursue that point, but will 

 group together, as in the penultimate line of the table, the 

 blacks and reds as "pigmented, not blue," and assume 

 that the three classes should occur in a 1:2:1 ratio. Do 

 the actual results bear out this assumption, having regard 

 to the errors of sampling? 



Examining the last two lines of the table, it is clear that 

 each observed class, taken by itself, is by no means an im- 

 possible approximation to what would be demanded by a 

 1:2:1 ratio. The blues and the "pigmented not blues" 

 fall outside the range for which the probability is ^ but 

 only slightly outside. It would be practically an even 

 bet, if Blue Andalusians really follow a law of 1:2:1 

 segregation when bred together, that any particular sam- 

 ple of 58 offspring would show in each particular class as j 

 great a deviation as the present sample.^^ 



Now we may consider in detail the mode of calculating | 

 the figures in ihe last line of Table I. 



13 Always on the assumption, of course, that it is legitimate to lum 



