CONTENTS 



Preface f> 



Introduction 6 



PART I. LIFE PROCESSES 



Material and method 11 



Body weight at birth 14 



Growth in body weight 15 



Variability in body weight 34 



The reproductive period 41 



Fertility 45 



Sterility 4! 



The sex ratio 55 



Mortality 59 



Behavior 63 



Summary 68 



Literature cited 70 



PART II, SERIES 1. OBSERVATIONS ON THE BODY MEASURKMKXTS AND ox THE 

 WEIGHTS OF SOME ORGANS OF CAPTIVE GRAY NORWAY RATS 



Material and procedure 73 



Body length 74 



Body weight on observed body length standard: wild gray Norway 7(5 



On the weights of the several organs 77 



Introduction 77 



On the weight of the brain and of some of its parts 7s 



Parts of the brain - 



On the weight of the hypophysis 83 



On the weight of the thyroid 87 



Weight of both suprarenals '''-' 



Weight of gonads 95 



PART II, SERIES 2. ON THE PARTS OF THE SKELETON IN THE CAPTIVE GRAYS. 97 



Discussion 1"" 



Conclusions 1 ( "> 



Literature cited ' '"> 



