Training does not increase the sensitiveness of a sense organ.
But by means of which sense organ was it received by the horse?
Time is no force that could conceivably act as a stimulus to a sense organ.
If there is no stimulation of a sense organ, there is no sensation, no perception.
We said just now, that a nerve begins in a sense organ and ends in a muscle.
A perception, then, results from the stimulation of a sense organ.
It is a general rule of the nervous system that no nerve cell extends without a break from any sense organ to any muscle fiber.
A nervous activity which consists of the passage of a disturbance from a sense organ to a muscle is called a reflex.
A big bunion is as good as a sense organ, but his feet are too small and elegant.
On the physical side there is need for the adaptation of the sense organ and the body to the situation.