The table given below indicates the various changes which occur in the mouths of ruminants, and more particularly in the mouth of the ox:

RUMINANTS

—Incisors—

 

—Molars—

  Age

Temporary

Permanent

  Age

Temporary

Permanent

At or soon after birth

4

0

12

 0

2 weeks

6

0

1 year

12

 4

3 weeks

8

0

2 years

 8

12

2 years

6

2

3 years

 4

16

3 years

4

4

4 years

2

6

4 and 5 years

 0

24=32 

5 years

0

8

A table giving the number and variety of teeth as they occur in the domestic animals and in man may be serviceable as one of handy reference, and is herewith appended:

IncisorsMolarsCanineBicuspidTotal
Man 4
—
 4		 6
—
 6		 2
—
 2		 4
—
 4		= 32
Horse 6
—
 6		12
—
12		 2
—
 2		 0
—
 0		= 40
Ox 0
—
 8		12
—
12		 0
—
 0		 0
—
 0		= 32
Dog 6
—
 6		12
—
14		 2
—
 2		 0
—
 0		= 42
Pig 6
—
 6		14
—
14		 2
—
 2		 0
—
 0		= 44
Cat 6
—
 6		 8
—
 6		 2
—
 2		 0
—
 0		= 30

The dental formula of the ox is the same as that of all ruminants.

RESPIRATORY SYSTEM OF THE HORSE.

Organs of Respiration.—By the action of these organs certain chemical and physical changes take place in the blood, the chief of these consisting of absorption of oxygen from, and giving off carbonic acid to the atmospheric air, the former change being necessary for the elaboration of the fluid, the latter for the elimination of a substance which, if retained, would prove injurious. The organs of respiration are invariably adapted to the wants of the animal and the medium in which it lives. Thus insects breathe by air-tubes, opening on the surface of the body; in the oyster breathing is performed by fringes; in fishes by gills; in the mammalia by means of elastic air-receptacles, called lungs, which are enclosed in special cavities, and communicate with the atmosphere by means of an air-tube.

In the horse, who breathes only through his nose, the organs of respiration are the nostrils, nasal-chambers, larynx, trachea, and in the thoracic cavity, the bronchi, bronchial tubes, and the lungs.