Responses to the Physical Environment — Continued 
2. Trails, Orientation and the Utilization of Space — Continued 
E. Orientation in Space — Continued Page 
d. Presumed Order of Dominance of the Sense Modalities of Rats in Determining 
Spatial Orientation 79 
e. Observed Orientations of Individual Rats 79 
f. The Interaction of the Sense of Smell and Conditioned Routes of Travel Upon the 
Ability to Locate a New Source of Food 82 
F. Utilization of Space by Rats 82 
3. The Strange Object or Strange Situation Reaction 85 
A. Activity Recorders 85 
B. Food 86 
C. Birds 86 
D. Sound 86 
E. The Chain-Fright Reaction 87 
4. The Responses of Rats to Traps 88 
A. The Repeat Response 90 
B. The Recapture Response 90 
C. Summary of the Alteration of Trap Avoidance Through Time 92 
D. Trap Avoidance as Influenced by a Rat’s Associates 92 
E. Sexual Differences in Frequency of Capture 92 
F. Variability of the Trap-Avoidance Behavior 94 
G. Social Stress and the Proneness to Enter Traps 95 
5. Food, Water, and Elimination 99 
A. The Sources of Food 99 
B. Behaviors About the Source of Food 100 
C. Shelter Storage ' 102 
D. Factors Affecting the Intensity of Storage 105 
E. The Position of Food Caches in the Harborages 107 
F. An Extreme Development of Cache Formation 107 
G. The Nonrecognition of the Value of Food 107 
H. The Food Acquisition Component in the Syndrome of the Social Outcast 108 
I. Summary of Hunger Satisfaction and Storage Behavior 109 
J. Availability of Water and Behaviors Relating to Drinking 109 
K. Elimination Behavior 110 
6 . Activity 112 
A. Fluctuations in Intensity and Periodicity of Locomotor Activity 112 
B. Time-Space Utilization by Rats in Relation to Population Growth 123 
C. The Relationship of Temperature and Barometric Pressure to Intensity of Activity 126 
D. The Effect of Snow on the Amount of Aboveground Activity 131 
E. Observed Activity of the Rats as it Relates to Periodicity 132 
The Nature and Consequences of Social Behavior and Social Organization 136 
1. General Account of the Changes Occurring Throughout the History of the Colony 136 
A. Introduction and Adjustment 136 
B. Regional Differentiation of Major Social Groups 138 
2. Observations Concerning Young Rats from Birth to Sexual Maturity 143 
A. Death of Litters Shortly Following Parturition 143 
B. Some Case Histories of Mother to Young Relationships 144 
a. Litter 2 144 
b. Litter 3 145 
c. Three Litters of Female 43 147 
C. The Social Conditioning of Juveniles by Adults 148 
D. Period of Initial Sexual Behavior of Subadult Rats 131 
vi 
