146 Chapter IV. 



ignorant of the prudence of their actions, and uncon- 

 scious of duty. Under the guidance of sensitive cog- 

 nition and perception they follow the mysterious in- 

 stinctive impulse arising from their organic develop- 

 ment, which suggests to them the means necessary for 

 preserving their species. But they do not understand 

 the appropriateness of these means and need not reflect 

 how to use them to advantage. 1 



Wherever in the animal kingdom the care of the 

 young requires "family life," i. e., a regular co-habita- 

 tion of the parents and of the young, this task 

 takes place only as far as the preservation of the 

 species renders it necessary. The same organico- 

 instinctive.laws, to which breeding is subjected in 

 general, also determine the existence and firmness of 

 family ties as well as the extension of the family circle 

 with different species of animals. There is no room 

 for individual reason and liberty; and to postulate 

 them is not only wholly superfluous, but also contra- 

 dicted by innumerable facts. As birds associate in 

 pairs only during the mating season for the preserva- 

 tion of the species, so in building their nest and in 

 hatching their young, the two mates co-operate like- 

 wise only as far as is necessary for preserving their 

 species; and the pairs remain together and in com- 

 pany with their young no longer than the same purpose 

 requires. Altum, in his excellent book "Der Vogel. 

 und sein Leben", has supplied us with a number of 

 striking instances, proving how ridiculous and unten- 



1 ) We have so minutely proved this fact in the case of insects that 

 live single, in our book, "Der Trichterwickler, eine naturwissenschaft- 

 liche Studie ueber den Thierinstinct" (Chap. IV. ff.), that there is no 

 need of repeating the proof here. 



