Abstract
The distribution of alkaline phosphatase in insect tissues has been studied by a histochemical technique. The enzyme is widely distributed in the alimentary tract, storage tissue, nervous tissue, in parts of the reproductive system, in certain muscles, and some glands. It thus appears to be inv~lved in a variety of functions. Many examples of both the histological and cytological distribution are explained by the relation of the enzyme to mechanisms of transport across cell boundaries. But a function of this kind is not evident in such sites as muscles and nerves. The presence of deposits of inorganic phosphate in the alimentary tract and malpighian tubules of some species is recorded.