THE CHRYSALIS. 45 



tension in front. It may also be noticed that 

 chrysalids with extraordinary projections or ridges 

 in other parts of the body all belong to the same 

 free-moving groups [Fig. 62 ; see 

 also Fig. 59] ; the greater the dan- 

 ger to the chrysalis from sur- 

 rounding objects, the greater its 

 protection by horny tubercles and 

 roughened callous ridges ; the 

 greater the protection possessed in 

 other ways, as by firm swathing or 

 a safe retreat, the smoother the sur- } g l - f 

 face of the body and the more reg- 

 ular and rounded its contours. 



During the caterpillar stage, the three joints 

 corresponding to the thorax of the future butter- 

 fly are of nearly equal size, each having one pair 

 of legs ; in the butterfly, however, the second and 

 third joints also bear the wings, which become 

 the principal, we might almost say exclusive, 

 organs of motion ; these joints therefore are devel- 

 oped at the expense of the first ; and as the front 

 wings are always larger than the hinder pair, and 

 by their position require more muscular force, 

 the joint of the thorax which supports them is 

 always proportionally larger. The preparation 

 for this necessity is seen in the chrysalis, where 

 the wings are already developed ; to a great ex- 

 tent this is true even in the blues and their allies, 



