EFFECTS OF TEMPERATURE. 11 



execute them so well. We must necessarily conclude 

 that it has been instructed by a GREAT MASTER; for He 

 who has rendered it necessary for the insect to undergo 

 this change, has likewise given it all the requisite means 

 for accomplishing it in safety," 



If we examine a chrysalis we are able to make out, 

 through the thin envelopej all the external organs of 

 the body stowed away in the most orderly and compact 

 manner. The antennae are very conspicuous, folded 

 down alongside of the legs ; and precisely in the centre 

 will be seen the tongue, unrolled and form ing a straight 

 line between the legs. The unexpanded wings are 

 visible on each side very small, but with all their 

 veinings distinctly seen ; and the breathing holes, 

 called spiracles, are placed in a row on each side of the 

 body. 



The duration of the chrysalis stage, like that of the 

 egg, is extremely variable, and dependent on difference 

 of temperature. As an instance of this, one of our 

 common butterflies has been known to pass only seven 

 or eight days in the chrysalis state ; this would be in 

 the heat of summer. Then, in the spring, the change 

 occupies a fortnight; but when the caterpillar enters- 

 the chrysalis state in the autumn, the butterfly does 

 not make its appearance till the following spring. 

 Furthermore, it has been proved by experiment, that if 

 the condition of perpetual winter be kept up by keep- 

 ing the chrysalis in an icehouse, its development may 

 be retarded for two or three years beyond its proper 

 time; while, on the other hand, if in the middle of 

 winter tha chrysalis be removed to a hothouse, the en- 

 closed butterfly, mistaking the vivifying warmth for 

 returning summer, makes its debut in ten days or a 

 fortnight. 



