He then went to McGill University, and in 1927 took a zoology chair at the University of Cape Town. He worked in endocrinology, studying chameleon properties of the Xenopus frog. The frog's adult color depended on its early environment; wild frogs became brownish-green, while frogs raised in a dark environment became black, and in a light environment, light-colored. Hogben theorized that the frog's ability to develop differences in color was related to the pituitary gland. After removing the pituitary gland, the frogs became white regardless of their environment.