106 HELEN DEAN KING AND HENRY H. DONALDSON 



in weight slightly. Unfavorable conditions produce organs 

 of smaller weight, but though this response takes place, the 

 body length remains unchanged and the body weight is but 

 slightly affected. 



CONCLUSIONS 



After ten generations in captivity, the captive Gray differs 

 from the wild type as follows : 



There is an increase in body weight on body length. A 

 slight increase in the weight of the hypophysis. No change 

 occurs in the weights of the gonads. Less in weight are the 

 brain, the thyroid, and the suprarenals, especially the female 

 suprarenals. 



In organs of lesser weight the greater loss occurs at 

 GI, but there is no subsequent progressive loss, save in the 

 thyroid. 



Similarly, the captive Gray compared with the Albino 

 shows the following relations : 



The brain, the suprarenals (especially in the male), the 

 gonads, and the bones are still heavy. Body weight on body 

 length and the weight of the thyroid are similar to those for 

 the Albino. 



The hypophysis, especially that of the female, remains less 

 in weight. 



Ten generations of captivity have, by no means, served to 

 give the captive Grays the organ constitution of the Albino. 



In view of the preliminary character of this report, no 

 survey of the literature will be attempted at this time. 



LITERATURE CITED 



DONALDSON, HENRY HERBERT 1924 The Rat : Data and reference tables, 

 2nd ed. Philadelphia : The Wistar Institute of Anatomy. 



HAMMETT, FREDERICK S. 1922 Studies of the thyroid apparatus. VII. A dif- 

 ferential effect of thyro-parathyroidectomy and parathyroidectomy on 

 the incisor teeth of the albino rat. Am. J. of Physiol., vol. 62, pp. 

 197-201. 



HATAI, SHINKISHI 1914 On the weight of some of the ductless glands of the 

 Norway and of the albino rat according to sex and variety. Anat. 

 Rec., vol. 8, no. 12, pp. 511-523. 



