When the dog is repeatedly teased with the sight of objects inducing salivary secretion from a distance, the reaction of the salivary glands grows weaker and weaker and finally drops to zero.

While you are experimenting, do not remain content with the surface of things.

Don't become a mere recorder of facts, but try to penetrate the mystery of their origin.

Learn, compare, collect the facts!

When the dog is repeatedly teased with the sight of objects inducing salivary secretion from a distance, the reaction of the salivary glands grows weaker and weaker and finally drops to zero.

As we have seen, bread, and especially dry bread, evokes secretion of considerably larger quantities of saliva than meat.

It is not accidental that all phenomena of human life are dominated by the search for daily bread - the oldest link connecting all living things, man included, with the surrounding nature.