Index 



^ 



Aggregations, in nature, 32; 

 hibernating, 32; breeding, 

 33; migrating, 33, 35, 37; 

 various examples, 34; co- 

 lonial animals, 41; forced, 

 42; feeding, 44; overnight, 

 46, 248; relation to social 

 life, 49, 272 



Alcohol, mass protection from, 



52 

 Alverdes, F., 29 

 Ancestral tree of animals, 86, 



87 



Antelopes, 37 



Ants, 26, 32; effect of num- 

 bers on digging, 139; im- 

 portance of females, 259; 

 castes, 262, 265 



Aphids, 272 



Appetite, social, 44, 47, 247 



Arhacia eggs, 69; spermatozoa, 

 69, 83; effect of numbers on 

 rate of cleavage, 71; effect 

 of extracts, 74 



Bacteria, mass protection, 67; 



food for protozoa, 77 

 Baker, O. E., 217 

 Bats, 36 

 Bavaria, population trend, 



223 

 Beebe, William, 248 



Bees, 26, 260, 262, 264, 265; 

 solitary, 46; importance, 

 259; castes, 260 



Beetles, hibernation, 32 



Behavior, of isopods, 20; 

 group, §2, 133; social cri- 

 teria of, 173 



Belgium, population, 226, 227 



Bennet, Mary, 185 



Birds, 33, 46, 47, 48, 88, 110, 

 134' 155' 175' 206, 250, 261 



Birthrate, 219 



Bison, 38 



Bonellia, 256 



Bowen, Edith, 92 



Breeding season, 33, 133 



Butterflies, overnight aggrega- 

 tions, 46 



Calcium, protective value, 65 

 Canaries, social order, 191, 



193, 207 

 Caribou, 37 

 Caste, 250, 274 

 Castle, G. B., 266, 267 

 Chapman, Frank M., 134 

 Chapman, R. N., 104 

 Chen, S. C, 139 

 Chickens, group stimulation, 



135; social order, 176, 190, 



193, 207; IQ, 192 

 Child, C. M., 58, 248 



