STRUCTURE. 35 



a moveable tympanic bone ; and on the upper part, this same 

 face is articulated, or united to the skull by elastic laminae ; this 

 mode of union leaves them, at all times, some degree of mobility. 



The horn which invests the two mandibles serves the place of 

 teeth, and is sometimes prickled, so as to represent them. Its 

 form, as well as that of the mandibles which sustain it, varies 

 infinitely, according to the nature of the food which each species 

 takes. 



The digestion of birds is proportioned to the activity of their 

 life, and the force of their respiration. The stomach is composed 

 of three parts ; the crop, which is a folding of the oesophagus; 

 the succentorial ventricle, a membranous stomach, furnished in 

 the thickness of its surface with a multitude of glands, the secre- 

 tion of which imbibes the food ; and finally, the gizzard, armed 

 with two powerful muscles, which two radiated tendons unite, 

 and lined within with a cartilaginous coating. The food is 

 ground there the more easily, by the bird swallowing little stones 

 to augment the force of the tituration. In a majority of species 

 which live only on flesh, or on fish, the muscles and the surface 

 of the gizzard are reduced to an extreme weakness ; it has the 

 appearance of making only a single bag with the succentorial 

 ventricle. The dilation of the crop is also sometimes altogether 

 wanting. 



The liver turns the bile into the intestines by two conduits, 

 which alternate with the two or three by which the pancreatic 

 fluid passes. The pancreas of birds is large, but their spleen is 

 small ; they have no epiploon, the uses of which are in part 

 supplied by the partitions of the air-cavities. Two appendages 

 are placed toward the origin of the rectum, and a short distance 

 from the anus; these are more or less long, according to the 

 food of the species. The herons have them very short ; other 

 genera, as the pici, are without them altogether. 



Every one knows the varied industry employed by birds in 

 constructing their nests, and the tender care they take of their 

 eggs and of their young ; this is the principal part of their in- 

 stinct. For the rest of their intellectual qualities, their rapid 

 passage through the different regions of the air, and the lively 

 and continued action of this element upon them, enable them to 

 anticipate the variations of the atmosphere in a manner of which 

 we can have no idea, and from which has been attributed to 

 them, from all antiquity, by superstition, the power of announcing 

 future events. They are not without memory or imagination, 

 for they dream ; and every one knows with what facility they 

 may be tamed, and may be made to perform different operations, 

 and repeat certain airs and words.* 



* See Griffith's Cuvier, vol. vi. p. 3. 



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