THE PUBLICATION or THIS RESEARCH WAS FINANCED BY 

 "THE DOCTOR CARLOS F. MAC-DONALD RESEARCH FOND" 



LIFE PROCESSES AND SIZE OF THE BODY AND 



ORGANS OF THE GRAY NORWAY RAT DURING 



TEN GENERATIONS IN CAPTIVITY 



PART I. LIFE PROCESSES 

 HELEN DEAN KING 



PART II. SIZE OF THE BODY AND ORGANS 



HENRY H. DONALDSON 

 The Wistar Institute of Anatomy and Biology 



TWENTY-TWO CHARTS 

 PREFACE 



When it was recognized that the mutant albino rat differed 

 from the ancestral gray Norway not only by the absence of 

 pigmentation, but also in the proportional development of its 

 organs, an attempt was made to feralize the Albino. This 

 was done by planting Albinos where they might lead a wild 

 life, in order to see how far, under these conditions, they 

 would return toward the ancestral type. Five such colon it-- 

 were planted in localities ranging from the Ipswich sands 

 in Massachusetts to the dry Tortugas in the Gulf of Mexico, 

 but for various reasons all of them failed. This first effort 

 to determine whether the albino rat would revert, under \\ild 

 conditions, to the gray Norway type, having thus met diffi- 

 culties that halted it, the problem was n-vi>ri|, ;md it \\a- 

 next considered whether captivity and the accompanying 

 treatment applied to the wild gray Norway miirht n-diu-r it 

 to the organ constitution of the Albino. Observations along 

 this line seemed worth making, as we have no scientific iv<-nl 

 for any of our domesticated animals which show how do- 

 mestication has changed them from the wild typos from 

 which they came. 



