No. 605] 



ANIMAL COLORATION 



271 



no slight clei^artiire from one in the direction of the other 

 could have selective value. 



4. The non-appearance of intermediates when a form 

 which is assumed to have been derived from another by 

 selection of a series of heritable variations (mutations) 

 is crossed back with the original. 



5. The apparent fact that the three females of the poly- 

 morphic oriental butterfly, Papilio polytes, occur in pro- 

 portions which are approximately the same now as fifty, 

 or possibly one hundred and fifty years ago, although it 

 may be demonstrated mathematically that if either of the 

 two mimetic forms possesses even a slight advantage 

 over that from which they are assumed to be descended, 

 this should have appeared in an altered ratio while they 

 continue to live and breed together under the same con- 

 ditions. 



6. The fact that certain variations induced by differ- 

 ences in temperature or humidity are not directly in- 

 herited, since it is alleged that this limits the material 

 upon which selection might be supposed to operate. 



Of these points the first three may be more conven- 

 iently considered later with other common objections to 

 current hypotheses of mimicry. The remaining three will 

 be next examined in order. 



Punnett accepts Fryer 's^^ conclusion that in P. polytes 

 the two supernumerary females which resemble P. aris- 

 tolochia and P. hector differ genetically from the third 

 female (which resenililes tlio male) to the extent of one 

 and two Mendeliaii tnctor,-. ivs) .c-tivdy. II." r\\r< tlie 

 fact that there are I'ornis (.r swcci pea-, for ('\;niiple, 

 which are known to have arisen as sudden ^pcri-. and 

 behave in heredity as though they differed from the loo- 

 mal by a single factor. Hence he infers from analouy. 

 first, that the two mimetic butterflies sprang IVom t!i<' 

 primitive typo by r)no or tw.. mutations, as tlio cmm' iiiav 

 1h'. an. I, n> a corollary, that i'rsoniblaii<-o to tluMr uuu\.\. 



