THE LONGS. 
259 
CHAPTER X, 
SKETCH OF THE INTERNAL ORGANIZATION OF THE HORSE. 
THE LUNGS. 
PLATE IX. Fig. 1., &c. 
The lungs are two spongy bodies formed for the purpose 
of breathing. They are contained in the lateral regions on 
each side of the chest, a, a 9 a , separated from each other by 
the mediastinum and heart, which occupy the middle 
region. The lungs are two in number,—the right and the 
left, partitioned from each other by the mediastinum. They 
are further divided into lobes, that on the right side, which 
is the larger of the two, consists of three lobes, and the left 
has only two. These lobes are merely partial divisions, of 
variable extent, which serves to adapt them more accurately 
to the cavities of the chest, and at the same time render 
them fitter for the purposes of expansion and contraction. 
When the windpipe enters the chest, it is divided into two 
Branches, one extending to each lung ; and when these 
enter the substance of the lungs, they separate into nume¬ 
rous branches, each terminating in a little bag or cell. 
These bear a considerable resemblance to minute bunches of 
grapes. Around these cells are spread innumerable blood¬ 
vessels, being the extreme ramifications of those which con¬ 
veyed the blood from the right side of the heart to the 
lungs, and the commencement of those which conduct it 
back from the lungs to the left side of the heart. These 
