346 SYMBIOGENESIS 



their metamorphosis with leaves of Lactuca sativa or Atropa belladonna, 

 not one of the imagines produced resembles the original form ; when 

 the insects have been fed on lettuce the white ground-colour of the wings 

 predominates; when fed on deadly nightshade the brown markings of 

 the upper wings often coalesce and the white vanishes; in like manner 

 the blue markings on the lower wings fuse together and displace the 

 orange-yellow ground-colour. To which I may add, that, according to 

 Koch's work, The Lepidoptera of South-West Germany, feeding with 

 belladonna and poppies produces dark-coloured imagines. Koch made 

 experiments with similar results on Chelonia plantaginis and Gastro- 

 pacha pini. Finally, he refers to experiments with similar results on 

 species of Militcea and Argynnis, as already known. 



Must not, concludes Koch, similar processes occur equally, and even 

 on a larger scale, in the natural life of the countless forms of the class 

 in question? When a great number of individuals perish through an 

 occasional scarcity of their proper food-plant, must not nevertheless 

 considerable numbers survive by contenting themselves with other allied 

 food materials, and so give rise to varieties whose origin we do not 

 dream of, and which therefore we are led to regard as new species ? 



Speaking more broadly than Prof. Eimer, I would say 

 that it is fluctuations of symbiogenesis that determine 

 evolutionary changes. 



We are further told that : 



It is a physiological demand that constant, regular, not excessive 

 use of any organ is absolutely necessary to its maintenance. Indeed, 

 the stimulus to which it responds is undoubtedly the influence to which 

 an organ owes its origin and its gradual evolution. 



We have seen that this physiological demand is also pre- 

 eminently a bio-economic and symbiogenetic demand, and that 

 the recognition of this is essential to a real understanding of 

 evolutionary developments. 



As regards "Intelligence, Reason, Habit and Instinct," 

 Prof. Eimer has the following remarks : 



I conceive the distinction between intelligence and reason in the 

 following way : Intelligent actions are those which only have in view 

 the momentary and immediate personal interests; reasonable action is 

 that which also considers in relation to its experience and faculties the 

 general interests fellowmen and the future, knowing that by so doing 

 personal interests are doubly protected or which depends on general 

 conclusions. These definitions by no means imply that there are no 

 animals which act according to reason. Indeed, it can be proved by 



