PUPJE HATCHED BY A HEN. 259 



means of increasing the number of its broods." 

 This remark deserves much consideration. 



He was now anxious to try whether, by apply- 

 ing a more equable method of warming, he could 

 succeed in hatching pupse as he had done in the 

 hothouse. The idea occurred to him of endea- 

 vouring to hatch them under a hen. He concluded 

 that the warmth of the mother's breast would quite 

 as easily hatch the insects, as it does the eggs, 

 But there was this obstacle in the way: How 

 could he prevent the fragile and tender bodies of 

 the insect pupae from being crushed and killed by 

 the weight of the hen's body ? and, as we would 

 also suggest, How could he ensure that the bird 

 would not actually have eaten up the objects of 

 his care ? Aware of the fact, that, when a hen is 

 in the humour to sit, she will often allow smooth 

 stones to be placed among her own eggs, he 

 anticipated no difficulty on that score, and he 

 hit upon the following ingenious experiment: 

 He procured some hollow glass balls which he had 

 caused to be made as nearly as possible similar in 

 size and shape to the eggs themselves. Into these, 

 by an opening at one end, he introduced seven or 

 eight pupa3, and stopped the mouth up with a 



