Abstract
Experimental evidence of immunity to helminth parasites is on the whole very scanty. Several workers have drawn attention to the fact that immunity can be acquired as a result of age alone. Ransom (1921) using Syngamus trachealis in chickens, Herrick (1925) with Ascaridia lineata also in chickens, Sandground (1928) with Strongyloides and Nanophyes in dogs and cats, are three examples.