FORMS OF EGGS. 



43 





a, the egg of the meadow brown butterfly, magnified; h, egg of 

 the brimstone-moth (^Rurnia Cratcegata), magnified. 



The design of the appendages to some sort of 

 eggs is much more apparent, and affords us some 

 admirable illustrations of prospective contrivance. 

 The eggs of the ephemerae, for example, are smooth 

 and oblong, resembling caraway comfits, a form 

 which Svvammerdam proved to be admirably adapted 

 for diffusing them through the water, where, he says, 

 they are dropt by the mother insect. For this pur- 

 pose he placed '* a few of them on the point of a 

 knife, and letting them fall gently into water, they 

 immediately separated of themselves in a very curious 

 manner*." The same accurate observer describes a 

 very remarkable appendage in the egg of the water- 

 scorpion (Ncpa cinerea, Linn.), an insect by no 

 means rare in Britain. This egg is furnished with 

 a coronet of seven bristles disposed like the down 

 on the seed of the blessed thistle, (Centaurea 

 benedicta, Willdenow) ; and before they are de- 

 posited these bristles closely embrace the egg next 

 to them in the ovary like a sort of sheath, as if a 

 chain of thistle-seeds were formed, by placing each 

 sMCcessively in the bosom of the down of the one 

 next to it. As the mother insect deposits these eggs 

 in the stents of aquatic plants, the bristles, which are 

 partly left on the outside, are probably intended *X) 

 * Swannn Book of Nature, i. 104. 



