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XL] have important pathological bearings— Filaria bancrofti, which, in its adult stage, inhabits the lymphatics of man. As regards the others, with the exception of F. loa, we have no knowledge of any serious pathological significance they may possess. There can be no question of the importance in tropical pathology of F. bancrofti; there is abundant reason to believe that it is the cause of endemic chyluria, of various forms of lymphatic varix, and of other obscure tropical diseases, including, probably, elephantiasis.

Synonyms.— Filaria sanguinis hominis; F. nocturna; F. wuchereri. Geographical distribution and prevalence.— The geographical distribution of Filaria bancrofti is very extensive. It has been found as an indigenous parasite in almost every country throughout the tropical and sub-tropical world, as far north as Spain in Europe and Charleston in the United States of America, and as far south as Brisbane in Australia. In many places— South China, for example— quite 10 per cent., and in other places half of the population harbour it. I have ascertained that it is probable that one-third of the inhabitants of at least one district in India— Cochin— carry blood filarise. I also find that in some of the South Sea Islands— Samoa, for example fully one-half of the people are affected in this way. Thorpe has shown that in the Friendly Islands 32 per cent, of the people harbour this filaria. We have similar testimony as to the great frequency of the parasite in Madras from Maitland and others, in Demerara from Daniels, in several of the West India Islands from Low, in West Africa from Annett, Button, and Prout. Doubtless, if diligently and systematically sought for, it could be found in most tropical countries. Demonstration of blood microfilariæ.— Whoever would investigate the subject of filariasis will find that, in order practically to comprehend the subject and to provide himself with abundant material