lO BIOLOGICAL LECTURES. 



mean of color on the part of the American as on the part of 

 the British eggs, and among the anomalous eggs there were 

 twenty-four times as many American extremes as British. 

 (It may also be of interest to add that the single British ^gg 

 was the last &g2, to be selected, that is, it presented the 

 least departure from the mean of the twenty-five anomalous 

 variations.) 



Eighty-two of the examples of extreme color-variation were 

 thus found to be American and eighteen British. That so large 

 a proportion of extreme variation in color was found among 

 the American eggs is interesting in itself, but a comparison 

 with the relative amount of extreme variation in shape, enhances 

 the significance of both results, for not only is the preponder- 

 ance of variation among American eggs very obvious, but in 

 both cases, in length and in shape, it is almost precisely the 

 same (8i :i9 in the first, 82:18 in the second). 



Our data, then, whether it be gathered from comparisons of 

 length, ratio of breadth to length, shape, or color, all point in 

 one direction ; and, granting that the sparrow since its intro- 

 duction has been comparatively free from the action of natural 

 selection, we may conclude that the predicted results of Pan- 

 mixia have been realized. 



The collection of a series of facts, for the mere support of 

 some favorite theory, ought not to be the purpose of biological 

 investigation. The relation that the facts may have to other 

 facts and the bearing that they may have upon collateral 

 theories should, at least, be indicated. 



The following questions naturally arise: 



Apart from the tendency to vary, is the new form, adopted 

 by the American &gg, the result of the selection of adaptive 

 adventitious or fortuitous variations, or is it " determinate," the 

 result of the direct action of a new environment } If due to 

 the direct molding influence of a new environment, is the vari- 

 ation ontogcnic, that is, does it occur anew and repeatedly in 

 each successive generation, in obedience to reiterated environ- 

 mental demands; or have the directive influences of the mech- 

 anism of heredity been so affected that the variation becomes 



