That the bot-flies normally (and a few others abnormally, but for short periods only) pass a very long larval stage in the stomach and alimentary canal of herbivorous animals is one of the greatest marvels of insect life. All other growing creatures, which normally breathe in free air, require a certain large amount of breathable oxygen; and they would be stupefied or killed by a much smaller percentage of carbonic dioxide and other fermentive gases of digestion than undoubtedly exist in the strange abode wherein the bot-fly maggots dwell during the entire period of their feeding career. It has been stated that fly maggots artificially ingested into the human system have emerged alive in a normal condition, but the repulsive and objectionable experiment is not stated to have procured well nourished and full grown normally pupating larvæ. Some of the maggots of human intestinal myiasis are not perhaps amenable to artificial culture up to the stage of final metamorphosis; and they do not appear to have developed a breed or new species with a distinct habit of life. All the credible accounts of human intestinal myiasis point towards some fly which is plural-brooded, and of which the larvæ develop rapidly and promptly quit the body all at once; otherwise more than one infection must have occurred. The tales of prolonged continuous breeding, with slow and prodigiously copious emergings at intervals, should be altogether discredited. It is an amply warranted criticism to say that recently published records by authorities, in an endeavour to comprise every reported instance of myiasic infection, seem to countenance mere coarse Gargantuan jokes. On the other hand, it is painful to read such a "cock-and-bull" story as that of the doctor about his elderly lady patient, up whose nostril a gravid female blue-bottle flew and successfully performed the prolonged and delicate operation of laying therein a large batch of eggs, in spite of all attempts to expel the invader by violent sneezing. Day by day the said doctor observed the terrible injury, and the symptoms accompanying the growth of the feeding maggots, whilst the injection of a spoonful of paraffin would have effected an instantaneous cure. CHAPTER V GENERAL LIFE HISTORY