412 On Birds tisiiig Oil from Glands, 



of the'bne, will go far to explain those of the other. The blood of 

 animals, although it appears, as it flows along the arteries and 

 veins, a perfectly homogeneous fluid, is, in reality, a very com- 

 pound one. It consists chiefly of water, in which is suspended' 

 a number of minute globules, and which holds in solution 

 several earthy and metallic salts. By analysis, chemists have 

 obtained from it muriate and subcarbonate of soda ; muriate 

 and sulphate of potassa, phosphates of magnesia, lime, and iron, 

 and a small proportion of sulphur. In some animals the 

 blood is red, in others it is colourless. The blood has been* 

 shown not only to possess life itself, but to be the material 

 by which the life of all the other parts of the body is sup^^ 

 ported. The sap, or circulating fluid, of plants, is not homo-^ * 

 geneous in its nature ; but, like the blood, is a very complicated -^ 

 substance. It is composed of a thin aqueous fluid, in which 

 numbers of exceedingly small globular bodies are observed 

 to float. It contains dissolved in it many saline ingredients ; 

 and there can be little doubt that future researches will 

 demonstrate that the sap, like the blood, is endued with life. 



(To be continued,) -^^^' ^^ ^^* 



nm 90 oJ 



Art. in. Ofi Birds using Oil from Glands-, ^^ for the Purpose (f 

 Huoricating the, Surface of their Plurnage,'' (See Voh lofpi W»)«'*. 

 B^ Charles Waterton, Esq. > . ,, s^^^l t^^jj 



' /,'i^^, , r,}* J , " Nardo perunctus." Hor. Epod. n^>fi\ ^l^U'j^ovAi 



Birds, in general, are much troubled with vermin. ■ 'AiVe?'^'' 

 applying the solution of corrosive sublimate in alcohol to th6^ 

 fresh skin of a bird, you will see an amazing quantity of in^- 

 sects coming out from all parts of the plumage, but especially * ' 

 from the head. They linger for a few hours on the extremi-^- 

 ties of the feathers, and then fall off* and die : they are of all '^ 

 sizes, from the full-grown insect down to the minutest little '^ 

 creature which has just entered into life and motion. No part 

 of the body of the bird is exempt from their annoyance; and^' 

 we may judge how much the birds suffer from it, by their ^f' 

 perpetual attempts to free themselves from the tormenting^* 

 attacks of the insects. 



People are apt to suppose that a bird is preening, or recti- 

 fying, its feathers, when they see it applying its bill to the'^*^^ 

 plumage, and running it down a feather, from the root to the '^ 

 extremity : but a man well versed in the habits of birdsf-*^^ 

 knows, when he sees the bird do this (except after it has got 



