THE introduction of 1-diethylcarbamyl-4-methylpiperazine (“Hetrazan”)(I)(Kushner, Brancone, Hewitt, McEwen, SubbaRow, Stewart, Turner, and Denton, J. Org. Chem., 1948, 13, 144) has been a major advance in the treatment of filariasis (see, inter nl., Kenney and