Number 

 of rat 



1 C?. 



2 9 . 



3 d. 



4 9. 



261 d. 



262 9 . 



263 d\ 



264 9 . 



265 d. 



266 9 . 



TEMPERAMENTAL DIFFERENCES IN ALBINO RATS 113 



Outbred Stock— Continued 



Experiment 

 Source and parentage Date of birth begun 



Wistar September — , 1914 . . . November 5, 1914 



Granby, 251 c A x 252 9 . .October 28, 1914 March 2, 1915 



<i « 



a 



u 



. .November 28, 1914. . . 

 Wistar, 3d x 4 9 November 25, 1914. . . 



Granby, 251 d x 252 9 . .November 28, 1914. 

 * Purchased of Abbie E. C. Lathrop, Granby, Mass. 



Inbred Stock 

 Source and 

 Number generation of Experiment 



of rat inbreeding Date of birth begun 



201 d Wistar, 14th August 8, 1914 October 14, 1914 



202 9 " " " 



203 d " " 



204 9 " " 



5(? " September — , 1914 November 5, 1914 



g 9 « a « 



7 qP a a « 



g Cj « « a 



211 d 1 * Wistar, 15th December 18, 1914 April 11, 1915 



212 9 * " " " 



213 d 1 * " " " 



214 9 * " " " 



215 d* " " " 



216 9 * " " " 



* Offspring of 201 cT x 202 9 . 



METHOD OF INQUIRY 



Observations were made for above strains of rat as nearly 

 as possible at the same age, and for the sake of comparability, 

 on the same day. Certain of the observations were made under 

 the natural cage conditions; others, under definite experimental 

 conditions and for very specific purposes. These two kinds of 

 data, contrasted as the naturalistic and the experimental, tend 

 to supplement one another. 



The naturalistic type of observation includes (1) observation 



