FERTILITY AND STERILITY IN DROSOPHILA 



345 



HISTORY OF THE STOCKS USED IN CROSSING 



1. The Woods Hole stock 



This is a wild stock that originally came from Woods Hole, 

 Massachusetts. How long it had been in captivity I do not know, 

 but when I took charge of the stock it showed a fertility of 77.3 

 per cent. The stock was tested at various times throughout the 

 year 1912-1913. The behavior of the fertility of this stock is 

 given in table 1. The stock was cultured en masse. 



TABLE 1 



Showing the fertility of the Woods Hole stock 



TIME TESTED 



September 11 to September — , 1912'. 

 September 16 to October — , 1912. . . 



January 20 to February 14, 1913 



June 28 to July 15, 1913 



July 15 to July 28, 1913 



August 7 to August 24, 1913 



August 17 to September 4, 1913 



October 21 to November 11, 1913. . 



PES CENT 

 FERTILITY 



77.3 

 75.0 

 70.0 

 63.4 

 59.7 

 71.7 

 83.6 

 73.0 



2. The inbred stock 



This stock originally came from Falmouth, Massachusetts. 

 During the course of the experiments brothers and sisters have 

 been selected and paired for over 26 generations. Its produc- 

 tivity was at the beginning of the experiments relatively high as 

 shown by the large number of offspring produced. On inbreed- 

 ing the stock gradually dropped in productivity as shown in 

 table 2. 



TABLE 2 



Showing the productivity of the inbred stock in successive generations of close 



inbreeding 



