310 INSECT TRANSFORMATIONS. 



salides were placed under a sitting bird, they would 

 be matured in a similar way as he had found them 

 to be in the green-house. The difficulty was to pre- 

 vent them from being bruised and crushed by the 

 bird, as they are much softer and more easily injured 

 than eggs. This he obviated by enclosing them in 

 hollow glass balls about the size of a hen's egg, which 

 at the same time as readily deceived the bird as a piece 

 of chalk passes with the eggs set to hatch under a hen. 

 The chrysalides which he first tried were those of the 

 small tortoiseshell butterfly (Vanessa Urticce), eight 

 of which, attached to square pieces of paper, were sus- 

 pended within the glass egg as near to each other as 

 possible, and placed under a hen on the 22d of June. 

 The aperture of the glass egg was closed, but in such 

 a manner as to leave a communication with the ex- 

 ternal air. The effect of the heat manifested itself 

 the first day, in the moisture exhaled from the chrysa- 

 lides, all the interior of the glass being covered with 

 minute drops of water, which he allowed to evaporate 

 by unstopping the glass, lest the moisture might spoil 

 his experiment. When it was dry, he replaced it 

 under the hen, and he observed no moisture exhaled 

 on the following days, the chief transpiration having 

 occurred in the first twenty-four hours. In about 

 four days the first butterfly that, perhaps, was ever 

 hatched under a hen made its appearance. He found 

 four more evolved next morning, and one on the suc- 

 ceeding day, the 28th of June. Those of the same 

 brood which were contained in a nurse-box placed in 

 a window, did not appear before the 5th, and some 

 not before the 8th of July, which was ten or twelve 

 days later. Two out of eight of the chrysalides which 

 had been enclosed in the glass egg died. He made 

 a similar experiment with the same success upon 

 several chrysalides of the peacock butterfly ( Vanessa 

 Jo). With the pupas also of two-winged flies and 



