Page:Tropical Diseases.djvu/760

708 instead of swimming larvæ. The ova of the filaria are not like the long, supple, slim, active, swimming larvae; they are passive, more or less rigid oval bodies nearly five times the diameter of the embryo coiled up in their interior. In consequence of their size and passive character the ova, unlike the normal free-swimming larvae, are quite incapable of traversing such lymphatic glands as, in the event of their escape from the parental worm, they may be carried to passively by the lymph-stream. It is an accepted fact in pathology that an essential element in the causation of elephantiasis is lymph stasis. I have ventured to conjecture that the stasis of lymph which eventuates in tropical elephantiasis is in some instances produced by embolism of the lymphatic glands by ova of the filaria. If ova are expelled by the parent filaria, it must be as a result of some hurrying of the process of filarial parturition. That this does occur sometimes the discovery, already mentioned, of filaria ova in the lymph fully proves. We can readily understand how, in consequence of mechanical injury, to which from her exposed position in the limbs she must be frequently subjected, or of some other cause, the parent filaria may miscarry. Should this happen, then the contents of her uterus will be expelled prematurely, and before the ova, normally lying at the upper part of her uterus, have become the long, outstretched, active larvae we see in the blood. If a crowd of these passive, massive ova are carried by the lymph -stream to the lymphatic glands of a limb, in the lymphatic trunks of which a female filaria is lying aborting, embolism of the afferent lymphatics of the glands must result and stasis of lymph in the limb ensue.

Inflammation necessary for the production of elephantiasis.— Lymph stasis alone does not produce elephantiasis; this has been proved by experimental ligature of lymphatic trunks. It may produce a form of œdema, but not true elephantoid hypertrophy. Should inflammation occur in an area of lymphatic congestion so produced, as it is very apt to do on the