Henze (1913 a) was able to localize the vanadium chromogen in certain blood cells which he designated as morulae (Maulbeerformen). […] This type of cell, which, as will be shown later, is probably confined to the Ascidiidae and Perophoridae, is hereinafter referred to as a "vanadocyte", in order to distinguish it from other types of morulae which do not possess the properties just described.
Source: wiktionary