Organs of Nutrition 139 
a dense mat of hair at one end of the stomach, the free 
ends of which point outward, brush-like, and prevent 
the accidental entrance of any small fish-bones which 
otherwise might get into the small intestine. The giz- 
zard of a cuckoo, when opened, often gives the impression 
of a similar coating of hair lining the entire organ, but 
these are in reality only the hairs of caterpillars upon 
Fic. 107.—Cluster of matted hairs in the stomach of a Snake-bird. 
which these birds feed, which have become detached 
and have lodged in the folds of the gizzard lining. 
When considering the crops of birds we noticed the 
curious way in which a pigeon feeds its young, by re- 
gurgitating a cheesy substance which forms in its crop, 
and we will now speak of something still more remark- 
able. The strange nesting habits of the hornbills are 
foreign to this volume, but we cannot leave the subject 
of gizzards without touching on the manner in which 
the male birds of this group probably feed their impris- 
