420 Studies in the Theory of Descent. 



greater the nearer the last stage is approached, 

 this variation in the marking depending simply 

 on the struggle between the green colour and the 

 more anciently inherited black. In this manner 

 there arises, especially in the fourth stage of the 

 German local form, an incredible mixture of the 

 most diverse markings, all of which can, however, 

 be very easily explained from the foregoing point 

 of view. 



The simpler and, as I am inclined to believe, 

 the older form of the transformation is presented 

 to us in the local variety Ligurica. In the last 

 stage, when 7.5 centimeters long, this form is of a 

 beautiful bright green colour without any trace 

 of black marking 4 (PI. VIII., Fig. 77). The 

 colour of the six orange warts which are situated 

 on each segment is also similar in kail specimens, 

 so that this stage is perfectly constant. 



Our German S. Carpini shows different cha- 

 racters in the fifth stage. It is true that individual 

 specimens occur which are entirely green without 

 any black, but these are rare ; the majority possess 

 a more or less broad black ring encircling the 

 middle of each segment (PI. VIII., Figs. 78 and 

 79). Those specimens in which the black ring 

 as become broken up into large or small spots 



t is true that I only reared one brood, but from this fifty 

 specimens were obtained. It would be interesting to know 

 whether this variety of the caterpillar is distributed -over the 

 whole of Southern Europe. 



