I am afraid we must confess that we are as yet very ignorant of many points connected with the life history of the _Filaria loa_. With the adult female parasite we have a limited acquaintance, but till now we are ignorant of the appearance of the male worm. The larvæ have been observed in the interior of the adult, but what their further course is, what transmigration may occur, ere they reappear as fully formed filariæ under the conjunctiva has yet to be discovered. The only observation that bears at all upon this question is that made by Dr. Manson and reported in Dr. Davidson’s work, that in one case of _Filaria loa_, the _Filaria diurna_ was afterwards found in the blood. With the view of ascertaining whether the _Filaria diurna_ was present in the blood of my patient Miss H⸺, and also with the view of getting a report as to her general medical condition, I got my friend Dr. Alexander Bruce to undertake the examination. It must, however, be borne in mind that in her case the filaria removed proves to be a male, and, unless she were affected with the female parasite as well, no embryos could be expected in the blood. _Report by Dr. Alexander Bruce, October 16th, 1894._—“Miss H⸺, missionary to Old Calabar, went there at the age of twenty-two, has been out there ten years altogether; first was out for two years, then furloughed for one year on account of an attack of intermittent fever which turned her hair grey, but was not otherwise very severe in type. Then she was out for four years and home for one year on furlough. Then was out for seventeen months, invalided home in January, 1894, for remittent fever, gastritis, and a form of dysentery and great anæmia. The remittent fever began in December, 1893, with delirium at beginning, and fever which rose daily to 102° and 103° F. She was sent to sea in ten days, and on the way home the temperature on one occasion rose to 107°; this was reduced by ice-pack. Improvement was slow, being retarded by the gastritis and dysentery, and the tendency to pyrexia did not abate till the end of June. The gastritis was indicated by intense pain (agony, she called it) in swallowing anything, whether solid or fluid. The bowels now move only once daily or less frequently, and the motions are accompanied by small flakes of mucus (formerly by blood). There was always great mental depression during the attacks of dysentery. “The arms became, since June, stiff and swollen, especially on awakening from sleep (whether at night or during the day), and the hands felt ‘numb,’ ‘dead,’ ‘as if asleep,’ or ‘as if they didn’t belong to her.’