170 
THE VETERINARY ART IN INDIA. 
effect animal (and perhaps muscular) motion, it must be acted 
upon by a power or antagonal principle, which is found in the 
natural stimulants, as the passions, food, &c. 
Thus there is a state of irritation, which every fibre in the 
body possesses, called irritability; and the antagonal power is 
termed stimulus. It is the action of this last on the former 
which produces life. 
The irritability is a property continually accumulating in every 
fibre throughout the body, and is for ever acted upon by the 
natural stimuli, as food, passions/heat, &c. This action supports 
a kind of equilibrium ; that is, the power must not be greater than 
the property, consequently health depends on their proper balance. 
Since the death of the celebrated Dr. Brown, who was the 
founder of this system, the irritability has been accounted for in 
the following manner, and supported by numerous very inge- 
nious yet simple experiments*. 
The atmospheric air is composed of two fluids, in about the 
following proportions; — nearly three parts of azote, which, of itself, 
cannot support life ; and the rest oxygen or pure vital air, which 
qualifies the former for respiration and combustion^. 
The vital air possesses a stronger attraction for blood than for 
azote, with which it is combined in the atmosphere; consequently, 
if the atmospheric air comes in contact with blood, the vital air 
leaves the atmosphere to reside in it. 
This process is effected in respiration, when we inhale. A 
quantity of atmospheric air comes in immediate contact with a 
considerable quantity of blood in the cells of the lungs, by 
which the pure vital air is separated and absorbed by the blood, 
while the remainder is exhaled by the breath. It is the vital 
principle of the air thus imbibed that is supposed to convey 
irritability to the system. 
The blood, replete with this irritable property, flows to every 
part of the body, and supplies the muscular fibres; as the fibre 
possesses a still stronger affinity for the vital air, now called irri- 
* Dr. Brown, in his Elements, not knowing the properties of irritability, 
calls it excitability ; that is, a power acted upon by excitement or stimuli: 
but he never accounted for the source that supplied the fibres with this 
property, which is now supposed, from a number of experiments, to be irri- 
tability. Dr. Darwin employed oxygen to account for hi6 theory of meta- 
physics. It will be understood, in the present instance, that oxygen is only 
employed for the animal fibre for the purpose of animal life. 
f 1 have not introduced hydrogen or carbonic acid gas, which are usually 
found in very small quantities in the atmosphere, as I imagine them to be 
mere emanations from the various operations $n the surface of the earth, 
and being by no means homogeneous to the atmospheric air. 
Every material, whether in a solid or fluid form, possesses an attractive 
power in different degrees; this power is termed chemical affinity, on which 
all the phenomena of chemistry, and perhaps of nature, depend. 
