The disappearance of the sweat from England after 1551, or its failure to come out again with the appropriate weather, is one of those phenomena of epidemic disease which might be made to appear less of a mystery by finding several more in the like case. A history of all the extinct types of infective disease would probably bring to light some reason why they had each and all died out. But an epidemic disease leaves no bones behind it in the strata; nor has the astonishing progress of science succeeded as yet in detecting palæozoic bacteria, although that discovery cannot be delayed much longer. Meanwhile we have to make what we can of the ordinary records. In our own time, so to speak, the sweat became extinct in 1551, and the plague in 1666; perhaps someone before long may be able to say that typhus died out (for a time) in Britain in such and such a year, and smallpox (for good) in such and such another. The surprising thing is that an infection which came forth time after time should have one day been missed as if it were dead. If the sweat had five seasons in England, why not fifty? Perhaps its career was short because the circumstances of its origin were transient and, as it were, accidental. But it may have been also subject to the only law of extinct disease-species which our scanty knowledge points to--the law of the succession, or superseding, or supplanting of one epidemic type by another. Other forms of epidemic fever, in the same pestilential class as the sweat, were coming to the front in England as well as in other parts of Europe. Thus, in 1539, a summer of great heat and drought, “divers and many honest persons died of the hot agues, and of a great laske through the realm.” The hot agues were febrile influenzas, and the great laske was dysentery. Again, in the autumn of 1557, there died “many of the wealthiest men all England through by a strange fever,” according to one writer[541], or, according to another[542], there prevailed “divers strange and new sicknesses, taking men and women in their heads, as strange agues and fevers, whereof many died.” Jones in his _Dyall of Agues_, describes his own attack near Southampton, in 1558, and calls it the sweating sickness.