in the blood of the respective hosts, and Noè has shown recently that F. labiato-papillosa is fostered and transmitted, like F. bancrofti and F. immitis, by an insect intermediary, to wit, the stinging-fly (Stomoxys calcitrans), amongst the cephalic muscles of which it undergoes development.
This slow development of L. loa would seem to account for the very frequent failure to find the microfilaria in the blood in cases in which mature parasites have been extracted, a circumstance which has been brought forward as an argument against the theory that mf. diurna is really the offspring of L. loa. Some time ago I was consulted by a lady who for seven years had been troubled with L. loa, and Calabar swellings, and had had three loas removed at different times from the neighbourhood of the eye. On examining her day blood I found it full of innumerable specimens of mf. diurna. That these microfilariæ were diurna was fully established by a series of carefully conducted observations carried on day and night for upwards of a week. The patient informed me that she believed the medical man who seven years before had extracted one of the loas from her eye had probably the specimen in his possession still. This I had an opportunity of examining. It was a mature female crowded with embryos in all stages of development, including free larval forms such as were found in the blood. It transpired that I had already, many years before, examined this specimen, and that, being interested in the subject, I had written for specimens of the day blood of this patient soon after the extraction had been made. On referring to my note-book I found a record of the result of my examination of this blood, and that no microfilariæ were then found. From this it is evident that the mature L. loa may be E resent in the tissues, and yet that embryos may be absent :om the blood. I cannot suggest an explanation of what is apparently an anomaly; but the fact is definitely ascertained, and explains how it is that in many of the recorded cases of loa infection the embryos have been absent from the general circulation. It may be that it is not until the gravid female arrives at some organ or tissue that she deposits her young in such a position that they can get access to the circulation, and that the wanderings for which these worms are so remarkable are an effort to attain this situation. It would be well for those who have the opportunity to look for the parasite at autopsies, especially in the serous cavities. Quite recently Penel stated that he had found mf. loa in the saliva and urine of a patient who presented this larval filaria in the peripheral circulation.
As yet it is impossible to estimate accurately the number of adult loas present in any given infection, although in advanced cases some idea of this might be got from the number of microfilariæ in the peripheral blood. As a rule it is safe to conclude that the particular loa that may show itself about the eye or elsewhere is only one of many. Thus, in 1903, Brumpt, at the post-mortem of a negro whose blood con-
