XXIII 



and the want of provisions which it brings with it. As a matter of fact, this 

 is a case of "-radual adaptation to climatical conditions, acquired in course of 

 time by means of the intellectual faculty, which adaptation has for its basis 

 a certain knowledge, originally acquired by experience, but which by a continually 

 o-rowino- and developing adaptation has become a custom and passed into an 

 hereditar}^ instinct. Something similar is ver}' likely the cause of the strong 

 impulse in many birds of the colder regions to migrate to warmer countries 

 at the approach of te cold season. The impulse of the birds to build nests 

 is ver}' likely of the same nature; it has for its basis a knowledge acquired 

 by intellectual activity and according to the development ot this knowledge, 

 it has passed into an hereditary inclination, which occurs in the different species 

 in various degrees of development. In many species this knowledge seems to be 

 wholly undeveloped as yet. The intellectual activity in the meantime continues 

 to increase that knowledge more and more ; the young birds have still much to learn 

 from experience, and what they thus learn is also gradually transferred in an 

 hereditary way. That fully developed psychical inclinations and impulses can 

 also become hereditary in man, is not to be doubted; thus psychiatry knows 

 very well as a morbid phenomenon the heredity in the impulse towards suicide 

 and even towards the special manner in which it is performed. An evidently 

 hereditary inclination exists also in many persons for certain religious or even 

 political views, though with historical certainty it can be proved that before a 

 certain date such an inclination cannot have existed in the ancestors of these 

 persons. Now where such facts can be demonstrated in higher animals, 

 analogously with our own intellectual operations, and which, as in the nest- 

 building of birds we also see manifested in connection with care for the off- 

 spring, there is no reason why we should not accept the same with regard to 

 a similar strong impulse in many insects, both as regards the gathering of its 

 own winter-provisions and the care for the future of its offspring. This, for 

 instance, is very strongly manifested in many Hymenoptera, in which the care 

 for its offspring presents itself in all its operations, as founded upon the know- 

 ledge of the wants of its progeny, though those insects themselves will never 

 see their progeny. When we have thus become convinced that knowledge, 

 acquired in that way by experience, can become hereditary and, moreover, in 

 consequence of the knowledge in question, can create an impulse to take 

 intellectual measures in its own behalf, then the said knowledge of the larva 

 of Adolias Adonia Cram, of its future pupal state and the measures that it 

 takes for it, become more conceivable. How different the imago, the chrj'salis 

 and the larva of a butterfly may seem to us, they are in reality nothing else 

 than three successive forms of the same living being and when we take it for 



