BIRDS IN GENERAL. 3A 



each other, are capable of bruising and attenuating the hardest sub 

 stances, their action being often compared to that of the grinding 

 teeth in man and other animals. Thus the organs of digestion are in 

 a manner reversed in birds. Beasts grind their food with their teeth, 

 and then it passes into the stomach, where it is softened and digested. 

 On the contrary, birds of this sort, first macerate and soften it in the 

 crop, and then it is ground and comminuted in the stomach or giz- 

 zard. Birds are also careful to pick up sand, gravel, and other hard 

 substances, not to grind their food, as has been supposed, but to pre- 

 vent the too violent action of the coats of the stomach against each 

 ether. 



Most birds have two appendices, or blind-guts, which, in quadru- 

 peds, are always found single. Among such birds as are thus sup- 

 plied, all carnivorous fowl, and all birds of the sparrow kind, have 

 very small and short ones ; water-fowl, and birds of the poultry kind, 

 the longest of all. There is still another appendix observable in the 

 intestines of birds, resembling a little worm, which is nothing more 

 than the remainder of that passage by which the yolk was conveyed 

 into the guts of the young chicken, while yet in the egg and under 

 incubation. 



The outlet of that duct which conveys the bile into the intestines 

 is, in most birds, a great way distant from the stomach ; which may 

 arise from the danger there would be of the bile regurgitating into 

 the stomach in their various rapid motions, as we see in men at sea; 

 xvherefore their biliary duct is so contrived, that this regurgitation 

 cannot take place. 



All birds, though they want a bladder for urine, have large kidneys 

 and ureters, by which this secretion is made, and carried away by one 

 common canal. " Birds," says Harvey, " as well as serpents, which 

 have spongy lungs, make but little water, because they drink but lit- 

 tle. They therefore have no need of a bladder ; but their urine dis- 

 tils down into the common canal, designed for receiving the other 

 excrements of the body. The urine of birds differs from that of other 

 animals : for, as there is usually in urine two parts, one more serous 

 and liquid, the other more thick and gross, which subsides to the bot- 

 tom ; in birds, the last part is most abundant, and is distinguished 

 from the rest by its white or silver colour. This part is found not 

 only in the whole intestinal canal, but is seen also in the wlide chan- 

 nel of the ureters, which may be distinguished from the coats of the 

 kidneys by their whiteness. This milky substance they have in 

 greater plenty than the more thin and serous part ; and it is of a 

 middle consistence, between limpid urine and the grosser parts of 

 the faeces. In passing through the ureters, it resembles milk curdled 

 or lightly condensed ; and, being cast forth, easily congeals into a 

 chalky crust." 



From this simple conformation of the animal, it should seem that 

 birds are subject to fewer diseases ; and, in fact, they have but few. 

 There is one, however, which they are subject to, from which quad- 

 rupeds are, in a great measure, exempt; this is the annual moulting 

 which they suffer; for all birds whatsoever obtain a new covering of 

 feathers once a year, and cast the old. During the moulting season, 



