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ANATOMY AND PHYSIOLOGY 
attachment (in which there are some lymphatic glands) 
to the posterior mediastinum. The lungs are extremely 
elastic in their substance, even so much as to squeeze 
out any air that may be thrown into them, and to 
become almost at once a solid mass, having a good deal 
the appearance, consistence, and feel of an ox’s spleen. 
The branches of the bronchise, which ramify into the 
lungs, have not the cartilages flat, but rather rounded ; 
a construction which admits of greater motion between 
them. The pulmonary cells are smaller than in quad- 
rupeds, which make less air necessary, and they com- 
municate with each other, which those of the quadruped 
do not, for by blowing into one branch of the trachea, 
not only the part to wdiich it immediately goes but the 
whole lungs are filled. As the ribs in this tribe do not 
completely make the cavity of the thorax, the diaphragm 
has not the same attachments as in the quadruped ; but 
is connected forwards to the abdominal muscles, which 
are very strong, being a mixture of muscular and 
tendinous fibres. The position of the diaphragm is less 
transverse than in the quadruped, passing more obliquely 
backwards, and coming very low on the spine, and 
higher up before, which makes the chest largest in the 
direction of the animal at the back, and gives room for 
the lungs to be continued along the spine. The parts 
immediately concerned in inspiration are extremely 
strong, the diaphragm remarkably so. The reason of 
this must at once appear, it necessarily requiring great 
force to expand the chest in a dense medium like water, 
especially too when the vacuity is to be filled up with 
