60 



G. W. Harris 



Nov. Dec. 



Jan. 



Feb. 



Mar. Apr. 



16 23 30 7 U 21 28 * 11 18 "25 1 8 IS 22 29 7 M 2' 26 •« 11 1g 

 -I ' 1 1 1 1 1 1 1 1— I 1 1 I ■ ■ ■ ■ ■ ■ ■ ■ I 



Lesion in 



ant. 



hypothalamus 



287 

 263 

 24129o| 



6 



Lesion in 



ant. 



hypothalamus 



299 292 314 



c 



Blank 



318 316 

 315 310 

 1305 302 300 

 1312 303 296 297 3071 



Fig. 1. Diagram to illustrate the eflFect of various operations on the brain on the onset of 

 estrus in the ferret. In this figure the height of the block indicates the number of anini.iis 

 which began to show vulval swelling each week. The numerals within the block identify 

 individual animals. The animals marked by an asterisk possessed lesions confined to the 

 thalamus. The solid vertical bars indicate the time of operation. (From Dono\an and 



van der Werff ten Bosch, 24.) 



