The digestive canal represents a tube passing through the entire organism and communicating with the external world, i.e. as it were the external surface of the body, but turned inwards and thus hidden in the organism.

He noticed that the dogs tended to salivate before food was actually delivered to their mouths and set out to investigate this "psychic secretion" as he called it. Pavlov's mother Varvara Ivanovna Uspenskaya (1826–1890) was a devoted homemaker. Pavlov’s laboratory housed a full-scale kennel for the experimental animals.

Ivan Pavlov devoted his life to the study of physiology and sciences making several remarkable discoveries and ideas that were passed on from generation to generation. From his childhood days Pavlov demonstrated intellectual brilliance along with an unusual energy which he named "the instinct for research". S.