784 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



TABLE XXVII. 



Correlation between Number op Spines in Sex-combs and Length 

 of Tibia, Series X, Generation 1. 



x = spines (sum of both legs). 



\Ax = 10.775 

 Ay = 41.38 



r = .1413 J- .066 



« = 1.7485 

 <rj/ = 1.461 



Summary. 



1. Inbreeding probably reduces very slightly the productiveness of 

 Drosophila, but the productiveness may be fully maintained under con- 

 stant inbreeding (brother with sister) if selection is made from the more 

 productive families. 



2. In crosses of a race of low productiveness and inclined to sterility 

 (race A) with a race of high productiveness (B) it has been found that 

 a female of race A does not have her fecundity increased by mating with 

 a male of race B, and conversely, a female of race B does not have her 

 fecundity diminished by a mating with a male of race A. Hence 

 every male not actually sterile furnishes an abundance of functional 

 spermatozoa. 



