That old connection between rats and plague had lately been examined afresh, chiefly by Dr. Turner, the Public Health Officer in Bombay, and the theory of the rat-flea had sprung into science. Contemplate a dead rat lying on your floor in the day-time, and you will find numerous fleas leaping up and down upon his body. If you are wise and prudent, you will rapidly pour kerosene over him from a distance, and then set him alight. For if, having seen him brewing in the air, you do not thus nip him in the bud, you are likely to fall a victim to the plague after sunset. A rat’s fleas are not the harmless, homely insects that we know. This species of flea has a special predilection for rats, and they will not leave their favourite home if they can help it, at all events by day. At night, when the rat is dead, they have to go, and then, as a last resort, they will take refuge on a human body for want of better sustenance. But with them they bring the germ that has killed the rat. Whether they themselves infect the rat in the first instance, or whether they only transmit from him a bacillus which the rat has developed from other origins, I have not discovered; but I suppose the latter. Nor am I quite sure whether the fleas die of plague themselves or remain immune. Anyhow, the theory is that when once they have passed the germ into a human being’s blood, the plague is assured. In a climate like India’s the most careful and cleanly people can never be secure against fleas, for, wash as they will, some insect or other is pretty certain to be biting them every minute of the day and night, and it is difficult to distinguish one bite from another. A further terror is that the little grey squirrel with paler stripes, which draws no distinction of race or riches, and swarms throughout India, even on the roofs of the wealthiest bungalows, is quite as much a favourite with the fleas as any rat could be. While I was in Poona they were climbing over my verandah and scampering across my floor by dozens, and I took a peculiarly personal interest in their health, which happily appeared excellent. The British Government was, at the time, buying rats alive at some fraction of a farthing a head. They had already purchased 25,000 in the town when I was there, and everywhere one met industrious Hindus carrying rats in cages to the official rat-collector. Whether the price was high enough to induce industrious Hindus to breed rats for the British market, I do not know. But I believe it was found that the reduction of the rat population gave the survivors such increased vitality that never had such active and powerful specimens of rat been seen before.