Page:Transactions of the Royal Society of Tropical Medicine and Hygiene, volume 1.djvu/184

156 attribute the local phenomena to the mechanical irritation of the adult worm as it forces its way through the connective tissue near the surface. The oedema which would result would be intensified by the rubbing and scratching which takes place as a consequence of the itching, and the intensity of the phenomena would depend, to a large extent, upon the sensitiveness of the individual's skin. We know, for example, how very differently a mosquito bite will affect different individuals.

But it is when we come to F. nocturna that we find an association with a long list of diseases, which include lymphangitis, abscess, varicose glands, lymphatic varix, lymph scrotum, elephantiasis, etc.—in other words, with a series of diseases connected with inflammation or obstruction of some part or other of the lymphatic system.

It is unnecessary for me to enter into a history of this worm, which is well known. Its association with the diseases I have mentioned dates from the seventies and early eighties of last century. It was then that Sir P. Manson published his valuable and interesting work on the periodicity of the embryos and their transmission by the mosquito, and made suggestions as to the connection of the worm in the system and the occurrence of certain diseases. I have only recently had an opportunity of perusing this work, and I must confess to a feeling of astonishment that these very valuable and suggestive observations, forming, as they really do, the foundation of the present progressive position of tropical medicine, should have been for so long allowed to pass with so little recognition from the medical profession, and apparently without their vast importance being realized.

Of recent years there has been a marked advance in our knowledge of the distribution of filariasis, the methods