mammary glands

“[95] Quarterly Journal of Science, January, 1873, p. 116: “I can hardly believe that when a cat, lying on a shawl or other soft material, pats or pounds it with its feet, or sometimes sucks a piece of it, it is the persistence of the habit of pressing the mammary glands and sucking during kittenhood.””

Alfred Russel Wallace Letters and Reminiscences

“Kittens, puppies, young pigs and probably many other young animals, alternately push with their forefeet against the mammary glands of their mothers, to excite a freer secretion of milk, or to make it flow.”

The expression of the emotions in man and animals