Organs of Nutrition I 39 



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 



FIG. 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- 



