lymphatic system; elephantiasis, etc., are diseases due to obstruction of the l3nnphatic system, therefore they are associated. Of course this is putting it very briefly and crudely.
1. The coincidence between the geographical distribution of endemic elephantiasis and F. bancrofti is claimed as being one of the most important proofs of the connection between the two, and it is maintained that where F. nucturna is common, there elephantiasis is common, and vice versa. Now, the coincidence of the geographical distribution of elephantiasis and F. nocturna simply means that both are found universally over the Tropics. I do not propose to go into this at length, as it was so fully considered recently, but I should like to say that it was the disagreement between the knowledge of the prevalence of elephantiasis in a locality, and what I unexpectedly found to be the degree of filarial infection, which led me to doubt whether the connection was quite so clear. I had accepted the theory, but when I began to examine the blood in Sierra Leone, where elephantiasis exists but is not obtrusively common, and I found that a large percentage of the population was infected with filarial embryos, I must confess that I began to ask myself what the explanation of this was. In a paper on filariasis in Sierra Leone I showed that the average infection of the Colony and Protectorate was 21.4 per cent., varying from 173 in Freetown to 38.7 in one of the outlying districts. I also showed that the natives of Freetown themselves only showed an infection of 6.5 per cent. So far as filarial diseases were concerned, I showed that chyluria is very rare, that lymph scrotum is very rare, but that enlarged lymphatic glands are very common. Out of 1210 cases admitted to the Colonial Hospital in 1900, derived from all parts of the Colony, there were no cases of elephantiasis; in 1901 two cases of elephantiasis of scrotum and two of leg. In the Pro-
