1903.] 



Observations on the Sex of Mice. 



47 



3. y (B + a, born May 11, 1902). 



By A Oct. 2/02 4 — 



B Sept. 8/02 3 2 



„ B Oct. 18/02 2 3 



„ B Nov. 11/02 2 4 



„ D Aug. 20/02 4 4 



„ D Oct. 10/02 4 4 



„ F Sept. 19/02 4 3 



„ C 1 Nov. 25/02 2 7 



„ D 3 Dec. 12/02 3 5 



28 32 

 4. 8 (B + ft born July 16, 1902). 



This buck, when 4 weeks old, was placed in a large cage with the 

 following six does, all of which were under breeding age : B 1,1 , F 1 , 

 F 2 , D 21 , D 22 , C 1 ' 1 . The young of course were all mixed, but alto- 

 gether 27->J and 24 $ were born between November 9, 1902, and 

 January! 17, 1903. The buck was then put separately to five does 

 with the following result : — 



S • S ■ 



By B 2 Feb. 2/03 2 1 



„ C 1 Feb. 2/03 3 2 



„ D 1 Jan. 13/03 5 2 



„ D 1 Feb, 24/03 4 4 



„ B 2 - 1 Jan. 15/03 6 3 



„ O 3 .. Feb. 6/03 5 3 



21 11 



Previous record with young 



does 27 24 



48 35 



5. e (Bought September 6, 1902, at least 4 months old.) 



?. ?• 



By B 2 Sept. 25/02 A 2 



„ B 3 Oct. 1/02 4 5 



„ C 1 Sept. 27/02 1 6 



„ C 2 Sept. 22/02 2 4 



„ D 1 Oct. 5/02 3 4 



„ D 2 Sept. 30/02 4 4 



„ D 2 Oct. 23/02 4 3 



„ D 3 Sept. 29/02 1 4 



„ D 1 ' 1 Dec. 5/02 2 1 



25 33 



