160 Evolution and Adaptation 



are brilliantly colored. On this theory we also understand 

 the exceptions to these rules. We comprehend why Danaids, 

 Heliconids, Euploids, and Acracids, in fact all diurnal butter- 

 flies offensive to the taste and smell, are mostly brightly marked 

 and equally so on both surfaces, whilst all species not thus 

 exempt from persecution have the protective coloring on the 

 under surface and are frequently quite differently colored 

 there from what they are on the upper. 



" In any event, the supposed formative laws are not obliga- 

 tory. Dispensations from them can be issued and are issued 

 whenever utility requires it." 



Dispensations from the laws of growth ! Does not a 

 philosophy of this sort seem to carry us back into the dark 

 ages ? Is this the best that the Darwinian school can do 

 to protect itself against the difficulties into which its chief 

 disciple confesses it has fallen ? 



Weismann lays great emphasis on the case of the Indian 

 leaf-butterfly, Kallima inachis ; and points out that the leaf 

 markings are executed " in absolute independence of the 

 other uniformities governing the wing." 



"The venation of the wing is utterly ignored by the leaf 

 markings, and its surface is treated as a tabula rasa upon 

 which anything conceivable can be drawn. In other words, 

 we are presented here with a bilaterally symmetrical figure 

 engraved on a surface which is essentially radially symmetri- 

 cal in its divisions. 



" I lay unusual stress upon this point because it shows that 

 we are dealing here with one of those cases which cannot be 

 explained by mechanical, that is, by natural means, unless 

 natural selection actually exists and is actually competent to 

 create new properties ; for the Lamarckian principle is ex- 

 cluded here ab initio, seeing that we are dealing with a for- 

 mation which is only passive in its effects : the leaf markings 

 are effectual simply by their existence and not by any func- 

 tion which they perform ; they are present in flight as well 



