136 INSTINCT AND KEASON. 



able circumstances. Thus the new mental qualities deve- 

 loped by such physiological changes as maternity the 

 courage, affection, daring, self-sacrifice, which distinguish 

 maternal love in birds and so many other animals, may be 

 regarded as belonging to the category of latent instincts 

 ready to show themselves whenever the need for their display 

 arises. Other illustrations of dormant instincts, requiring only 

 to be roused into activity by some such slight impression on 

 the senses as a casual sight or sound, are to be found in the 

 desire for freedom being awakened in the domesticated goose 

 by the distant cries of its migrating wild fellows, leading 

 the former at once sometimes to join the latter, thereby 

 sacrificing all the advantages of man's association (Houzeau) ; 

 or in the Eskimo dogs in a team leaving their track and their 

 duty to follow game if it happen to cross their path, no com- 

 mand of the driver having then any power over them (Parry) . 



There is frequently a substitution or transposition of the 

 supposed distinctive instincts of one sex or species for those 

 of another; and this may occur naturally, but it more 

 generally happens under artificial and exceptional conditions, 

 as the result of association, imitation, or education. Such 

 instincts may variously be described as adopted, acquired, 

 unnatural, vicarious, and transferable. The phenomena of 

 foster parentage abound in illustrations of this class of trans- 

 ferred instincts, including, as they do, the assumption of 

 feminine duties by the male and the upbringing, by disap- 

 pointed barren females or by bereaved mothers, of the 

 young of other genera, species, or individuals. 



There is frequently also a signal perversion, vitiation, 

 or derangement of the natural instincts for instance, of 

 those of 



1. Self-preservation or love of life, in suicide. 



2. Love of young, in cannibalism. 



3. Love of proper food, in morbid appetite. 



4. Sexual desire, in erotomania. 



5. Destructiveness, in murder and self -mutilation. 



6. Acquisitiveness, in kleptomania, which includes useless 

 hoarding. 



7. Migration, in wholesale sacrifice of life. 



