“…Having been engaged for some time-see Tait (1910;1911, b)-in studying the blood corpuscles of certain Crustacea (Palinurus, Astacus, and especially Ligia), in all of which the same three types of corpuscle occur, each with its own peculiarities of movement, the question as to whether these different movements can rightly be termed amoeboid was forced upon my attention. In the case of two of the types, only one of which, the " explosive corpuscle," had been previously described with accuracy, it was evident that the movement is not amoeboid.…”