ON THE ROLE OF FILARIA. 153
are pretty sure to obtain filaria if we puncture a papule, especially as it is difficult to do so without drawing a little blood, and if we look carefully we will find another parasite in a large number of cases, namely, the Acarus scabiei. Craw-craw is, in my opinion, a very slipshod diagnosis to make; it is not a specific disease at all, but a term loosely applied by the natives of the West Coast of Africa to almost any form of skin eruption, including itch, ringworm, eczema, etc., aggravated as these are by dirt and the excessive action of the skin, and it can in all cases be classified among one or other of the well-known forms of skin disease.
I do not propose to discuss the question of F. medinensis. The clinical phenomena, inflammation, induration of the limb, sometimes sloughing and abscess, are recognised as being due to the presence of this worm and disappear with its removal.
F. LOA.
There are, then, only two left of any importance, pathologically, namely, F. loa and F. nocturna. The adult F. loa is a worm whose habitat appears to be the connective tissue, and which becomes visible when it approaches the surface in any situation where the tissues are thin and lax, as, for example, in the scrotum, the penis, and the conjunctivae, from all of which specimens have been excised.
Evidence is accumulating that a micro-filaria showing a certain amount of diurnal periodicity is the embryonic form of this worm, and I should like to bring before you a new case which illustrates this point, and two other cases where the presence of this worm was associated with certain cutaneous phenomena. The three cases were seen by me recently, and occurred in Europeans who had been for longer or shorter periods in the Calabar district of Southern Nigeria. In each of them the adult worm had been seen
