426 Studies in ttie Theory of Descent. 



are possessed more or less incompletely in the 

 fourth stage. Now since the developmental ten- 

 dency to the removal of black and to the pre- 

 dominance of green if we may thus venture to 

 express it is obvious in the fourth stage, we may 

 expect to find in the fifth stage a bright green 

 ground-colour, either without any mixture of black 

 or with such black spots and streaks as were 

 retained in the fourth stage as residues of the 

 original ground-colour. But instead of this the 

 fifth stage shows a dark green colour, and a more 

 or less developed black marking which cannot in 

 any way be derived from that of the fourth stage. 



The Genoese local form observed last year first 

 gave me an explanation to the extent that in this 

 form the last stage is actually only the potential 

 penultimate stage, or, more correctly expressed, 

 that the same characters which at present distin- 

 guish the last stage of this form, are already more 

 or less completely transferred to the penultimate 

 stage. 



The apparently paradoxical behaviour of the 

 German form can be explained by supposing that 

 before the pure bright green had become com- 

 pletely transferred to the penultimate stage a 

 further change appeared in the last stage, the 

 green ground-colour becoming darker, and black 

 transverse bands being formed. The marking of 

 the last stage would then be regarded as the 

 reverse of that of the preceding stage ; the absence 



