64 THE STRUCTURE AND LIFE OF BIRDS cuHap, 
once watched by an apparently trustworthy observer, 
at a repast which lasted for an hour and a half. Each 
time that the bird rose after diving, he saw the flash 
of a small fish and the jerk of the neck with which it 
was swallowed. And the total number of fish dis- 
posed of he estimated at one hundred and eighty. 
However small they may have been, it must have 
required a very large gullet to accommodate them. 
The stomach has two compartments, very different 
in their structure and function. There is the fore part, 
or Proventriculus, which is highly glandular, and the 
hinder part, which has no glands, and to which, when 
it is very muscular, as it is in many birds, the name 
of gizzard is given. The proventriculus secretes 
strong acid juices from its glands, and some kinds 
of food, such as meat, may, certainly in mammals, 
probably in birds, be partly absorbed here, the 
peptone, as it is called, that is formed from them, 
passing into the blood vessels that are separated only 
by a very thin membrane from the cavity of the 
stomach. It has been thought that the process is that 
called Osmosis, which is as easy to illustrate as it is 
difficult to explain. If a bladder containing peptone 
be held under water, a large quantity of the peptone 
will make its way out into the water, while the bladder 
will be distended by the water which has made its 
way in. Peptone is quite exceptional among solu- 
tions of organic matter in the readiness with which it 
passes through the walls of a bladder. White of egg, 
for instance, has been tried in the same way, and 
hardly any of it has escaped. 
The absorption of food into the blood-vessels is a 
