OF NATURAL HISTORY. 149 



There are many other inftances of ichneumon wafps and flies, 

 which, though they feed not themfelves upon worms, lay up pro- 

 vifions of thefe animals for the nourifhment of their young ; and 

 each kind is adapted to the conftitution of the worm that is to pro- 

 ceed from their eggs *. 



Birds of the fame fpecles, unlefs when reftrained by peculiar cir- 

 cumftances, uniformly build their nefts of the fame materials, and 

 in the fame form and fituation, though they inhabit very different 

 climates. When removed by neceflity from their eggs, they haf- 

 ten back to them with anxiety. They turn and fhift their eggs, 

 which has the effedl of heating them equally. Ducks and geefe 

 cover up their eggs till they return to the neft. A hen fits with 

 equal ardour upon eggs of a different fpecies, or even upon artificial 

 eggs. I have often contemplated with wonder an inftindl of the 

 fwallow. When her offspring are. very young, like other fmall 

 birds, flie carries their excrements out of the neft. But, after they 

 are older, fhe attaches herfelf to the fide of the neft, and, by fome 

 geftures and founds, follicits the young to void their excrements: 

 One of them immediately turns round, elevates its hind parts above 

 the edge of the neft, makes the proper effort, and the mother, before 

 the dung is half protruded from the anus, lays hold of it with her 

 bill, drags it out, carries it off, and drops it at a diftance from the 

 neft. In all thefe operations, men recognife the intentions of Na- 

 ture ; but they are hid from the animals who perform them. 



The fpider, the dermeftes, and many infeds of the beetle kind, 

 exhibit an inftindt of a very uncommon nature. When put in ter- 

 ror by a touch of the finger, the fpider runs off with great fwiftnefs: 

 But, if he finds, that, whatever direction he takes, he Is oppofed by 



another 



* Reaumur, torn. ii. pag. 38, 



