226 



BIOLOGICAL LECTURES. 



there appears on the left posterior wing of the cynthia an 

 orange area from which the black scales are absent. Again, 

 the promethea is of a slightly lighter red than usual. In the 

 second case, moreover, both components are typically colored, 

 except that the body of the promethea shades posteriorly into 

 red, a characteristic color of the female only. Whether these 

 departures from the normal coloration are due to abnormal 



FIG. 3. Operation of the second category. Union in " Tandem " of P. cynthia, 

 anterior, and C. promethea, posterior. 



conditions resulting from the severity of the operations, or 

 whether they are produced by the mixture of the different 

 haemolymph, is not sufficiently clear. 



The third group of operations is that producing "twins." In 

 these cases but little of either pupa was removed, so that two 

 practically entire moths, fused in various ways, result. Sixty- 

 nine pairs, altogether, were prepared, and fourteen of these 

 survived the metamorphosis. 



Taking the divisions of this group in order, the first to be 

 noticed are the "head to head" unions. The pupae were sec- 



