VENOMED PREY. 163 



and the withering drought of the equator, are alike 

 necessary for preserving the energy and the beauty 

 of the world. 



All preyers, and birds in an especial manner, as 

 being the most discursive rangers, are highly valuable. 

 They give play to the energy of life generally in that 

 which they individually destroy ; and but for them 

 the earth would become rank and foul with the 

 carcasses of those tribes which must perish and 

 be renewed in the different seasons. 



In the performance of these labours, many species 

 of birds have to prey upon animals, the immediate 

 contact of which with the body of the bird would be 

 attended with fatal consequences ; and in other cases 

 the prey is in places which the bird cannot, with 

 safety, approach too closely. The parts of birds 

 which are naked of feathers, whether they are co- 

 vered with horn or with skin, contain few muscles or 

 blood-vessels, so that they are not easily wounded or 

 otherwise injured in such a manner as to affect the 

 general economy and action of the bird. This is the 

 more necessary on account of some of the creatures 

 upon v/hich the birds feed being capable of inflicting 

 poisoned wounds, all of which would be painful in 

 the fleshy parts of the bird, and some of them very 

 speedily fatal. It does not appear that the animal 

 poisons, known by the general name of venom, are 

 deadly, or even in the least injurious, if they are not 

 taken into the circulating blood. Whether they 

 must be so taken by direct introduction into a blood- 

 vessel, in order to produce their fatal effects, or. 

 whether the poison may be carried into the circu- 

 lation by the lymphatics, which pour what they 

 collect into the veins through the thoracic duct, is 

 not clearly ascertained; but as the effect of those 



M 5 



