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774 order to prove this he fed a monkey on bananas concealing cyclops which had been infected for five weeks, and which contained fully developed larvæ. Six months later, when the monkey died, five worms were found in its connective tissues, all possessing the anatomical characteristics of D. medinensis. The evidence is now fairly complete that the life span of the female dracunculus extends to about one year, conforming probably to the habits of certain species of cyclops which, under natural conditions, serve as its intermediary host. It is not to be supposed that every species of cyclops is an effective intermediary; for, were this the case, guinea- worm would have a much wider geographical range.

Biological peculiarities explained.— The little we now know of the life-history of the guinea-worm explains many things that were formerly mysterious. We now understand why the parasite, on attaining maturity, makes for the legs and feet; these are the parts of the human body most likely, in tropical countries, to come in contact with puddles of water, the medium in which cyclops— the intermediary host —lives. We can understand, also, why it is that the contact of water with the skin of the host causes the guinea-worm to expel her young; and we can understand the rationale of the douching so much practised by the natives of certain of the endemic districts in their attempts at extraction. The water-carriers in India are said to be very subject to guinea-worm, which, in their case, is prone to appear on the back— that is, the part of the body against which the water-skin lies when being carried. On this fact has been based an hypothesis that the young guinea- worm enters by the skin. I would interpret the fact, if fact it be, by suggesting that the mature guinea- worm, conformably to her instinct, seeks out that part of the body most in contact with water, which, in the case of the Indian water-carrier, is his back.

Premature death of parasite.— Occasionally the guinea-worm fails to pierce the integument of her host; sometimes she dies before arriving at maturity. In either case she may give rise to abscess; or she