286 



RAB Bl T EX TERM IN A TION. 



In order to l^rini^ to a successful issue the method of ex- 

 terminating rabbits advocated by Mr. Rodier, and which has for 

 its motto, "Kill the females and let the males live," the na- 

 tural law of "survival of the fittest" must come into operation, 

 and it appears to have been accepted that when the males pre- 

 dominate and become the superior sex, the females necessarily 

 become exterminated. There, however, exists a theory, ac- 

 cepted by some as a natural law, which tends to avert the ex- 

 termination of a species by sexual preponderance, namely, the 

 theory of "cross-heredity of sex," the doctrine of which is that 

 the better nourished and superior parent tends to produce the 

 opposite sex. This theery of "cross-heredity of sex" is strongly 

 supported by the result of the test, for in pen Xo. i, (which ori- 

 ginally contained 9 does and 3 bucks) of the mcrease 15 were 

 females and 9 males; in pen No. 2, (originally containing 6 of 

 each sex) of the increase 21 were females and 4 males; in pen 

 No. 3, (originally containing 8 does and 12 bucks) 11 were fe- 

 males and 5 males; in pen 4, (originally containing 4 does and 

 12 bucks) 7 were females and 4 males; in pen 6, (originally 

 containing 11 does and i buck) 7 were females and none were 

 mjales. Pen 5 was apparently not used for breeding. 



The result of this test may be summarized as follows: 



1. Preponderance of males tended to decrease the number 

 of young. 



2. The males, when in excess, did not generally worry the 

 females to death. 



3. The males did not worry each other to any great extent. 

 It would appear that Mr. Rodier's method resolves itself into a 



pertinaceous effort to kill the last elusive doe. 



