114 FACULTIES OF BIRDS. 



the nature of gristle. This lining resembles the scarf- 

 skin of the human body in becoming- gradually thicker 

 by pressure and rubbing. Towards the cavity of the 

 stomach it forms folds and depressions, which on the 

 opposite surfaces are adapted to each other. The 

 cavity of the gizzard is comparatively small and 

 narrow, and its outlet is very near its entrance*. 



In many birds the outlet of the gizzard has no 

 valve or other mechanism to prevent a portion of the 

 contents from escaping before being duly digested, 

 and consequently a waste of the food swallowed 

 ensues, particularly when the bird has a very liberal 

 supply. Sir Everard Home is disposed to consider 

 these circumstances as intended by Providence to aid 

 in the dissemination of plants ; and Sir Joseph Banks 

 remarked to him that "the seeds which pass through 

 the gizzards of birds, without having been acted on 

 by the organs of digestion, are not only fit for vege- 

 tation, but have the period of their vegetating much 

 accelerated. The haws or berries of white-thorn 

 require being buried in the earth for a year before 

 they are fit to be sown ; but if turkeys are fed with 

 them in autumn, and the duns; is sown, the plants 

 begin to vegetate in the following spring. So ready 

 are the seeds that have passed through the intestines 

 of a bird to grow, that it is sufficient for them to be 

 enveloped in the dung of the bird without being 

 covered with earth, 



" At a country-house of Sir Joseph Banks, when 

 the family are from home, the blackbirds are in the 

 habit of perching on the iron rails of a stone staircase 

 leading up to the house, and a currant-tree, a way- 

 faring-tree,, and a yew-tree, grew up from the place 

 where they dropped their dung, and were evidently dis- 

 seminated by them. The various plants found in our 

 hedges, as the dog-rose, the briars, the bramble, the 

 common and water-elder, and a great variety of other 

 * Blumenbach, Comp. Anat. 100, 



