The Nature and Consequences of Social Behavior and Social Organization — Continued 
6. Growth, Health and Mortality — Continued 
A. Growth of the Individual — Continued Page 
g. The Nature of the Stress Associated With the Inhibition of Growth 233 
h. Trapping and Handling Rats as a Source of Stress Inhibiting the Maintenance of 
Weight 234 
i. The Question of Secondary Increases in the Rate of Growth 235 
j. Age and the Maintenance of Weight 235 
k. Place of Birth and Growth 235 
B. The Condition of the Pelage 236 
C. Health and Mortality as Observed Under the Field Conditions of the Experimental 
Colony 237 
a. Rats Found Dead or Dying 237 
b. Internal Strife and Cannibalism 238 
c. The Relationship of Flies to Health and Mortality 239 
d. The Relationship of Sex to Health and Mortality 240 
e. Relationship of Growth (Maturity Index) to Health and Mortality 242 
f. Infestation of the Rats by Microorganisms 243 
g. Social Rank and Growth as Factors Influencing the Prevalence of Infections with 
Microorganisms 244 
D. Population Growth 244 
Implications of the Study 247 
Abstract 249 
Discussion 253 
1. The Writer’s Attitude Toward the Study of Behavior 253 
2. Steiniger’s Study of Group Behavior of Rats 254 
3. The Rat as a Social Animal from a Comparative Point of View 255 
4. The Learning of Social Adjustments as a Factor in Determining Physiological Disturbance 
and Social Mobility 259 
5. Events and Conditions Relating to the Maternal Period of Life 260 
A. Stress Induced by Electro-Convulsive Shock in Relation to Adrenal Function, Growth 
and Maternal Behavior 260 
B. Effect of Litter Size on Growth and Later Behavior 261 
C. Size of Group 261 
D. Reinterpretation of the Wistar Institute Studies on Captive Gray Norway Rats 262 
a. Methods of Rearing and Selection 262 
b. Other Relevant Data from King’s Studies 264 
E. Maturation, Maintenance, and Decline of Reproductive Performance in Female Rats. . . . 264 
F. Manipulation of the Bond between Mother and Young 273 
G. Aggressiveness during Lactation 274 
6. Inhibition of Growth by Stressful Conditions 275 
7. Mortality in Rat Populations 277 
A. Decreasing Mortality Rate with Age 277 
B. Increasing Mortality Rates with Age 278 
8. The Significance of Social Class to Survival of a Population 280 
9. Strange Object Reaction and its Relationship to Periodicity of Activity 281 
10. The Role of the Physical Structure of the Environment 284 
