2L8 
ON THE STOMACH OF BIRDS. 
In most birds the stomach lies at the upper part of the abdo- 
men, that is, close to the spine, and rests, in a manner, on a 
stratum of intestines ; in the cuckoo , however, it lies below. This 
peculiarity does not belong exclusively to that curious bird, for I 
have found it in the ramphastos and the corvus caryocaiactes (the 
nut-cracker). 
The structure of the stomach differs most widely in the different 
orders and genera of this class. It appears merely as a thin mem- 
branous bag in several of those which feed on flesh and insects, 
when compared with the thick muscular globes of the granivorous 
genera. But there are both many intermediate links between 
these extremes, and, at the same time, considerable analogies in the 
structures, which are apparently the most opposite. This is parti- 
cularly observable in the course of the muscular fibres, and in the 
callous structure and appearance of the internal coat, in which 
points many membranous stomachs have a great resemblance to 
those of the gallince. 
Both parts, but particularly the muscular, are very strong in the 
gizzard ( ventriculus bulbosus) of granivorous birds. We find here, 
instead of a muscular coat, four immensely thick and powerful 
muscles, viz. a large hemispherical pair at the sides {later ales), 
and two smaller ones {intermedii) at the two ends of the cavity : 
all the four are distinguished both by the unparalleled firmness of 
their texture, and by their peculiar colour, from all the other muscles 
of the body. 
The internal callous coat must be considered as a true epidermis , 
since, like that part, it becomes gradually thicker from pressure and 
rubbing. It forms folds and depressions towards the cavity of the 
stomach, and these irregularities are adapted to each other on the 
opposed surfaces. The cavity of this curious stomach is compara- 
tively small and narrow; its lower orifice is placed very near the 
upper. Every part of the organ is, indeed, calculated for producing 
very powerful trituration. The numerous experiments which 
Reaumur performed in order to determine the extent of this tritu- 
rative power, are universally known. There are two curious ob- 
servations on this subject less generally known. Felix Plater 
found an onyx, which had been swallowed by a hen, to be dimi- 
nished by one-fourth in four days ; and a louis dor lost in this way 
sixteen grains of its weight. The end and use of swallowing stones 
with the food, the well known instinctive practice of granivorous 
birds, have been very differently explained. Ctesalpinus consi- 
dered it rather as a medicine than as a common assistance to 
