Ague, or Malaria, a fever characterised by recurring paroxysms in each of which a cold, a hot, and a sweating stage are present. When complete intermissions exist between the paroxysms we have to deal with intermittent fever, as distinguished from remittent, the more severe form, in which the fever only abates in severity but does not disappear between the attacks of shivering. The different varieties of intermittent fever have been classified according to the duration of the intermissions. Thus in quotidian ague there is a daily febrile paroxysm, in tertians the paroxysm occurs every third day, in quartans every fourth day, there being two clear days of freedom, and so on. Again, double tertians have been described in which ague fits occur every day, but those of the odd days present certain common characters, in which they differ from those of the even days. Ague is most common in tropical countries, but is limited tolerably definitely to certain spots, so that in many parts of the tropics it is unknown. It is now very uncommon for cases to originate in this country, though this was by no means true in former times. Agueish districts are frequently swampy, so that the affection is often known as marsh fever; the English expedition to Holland in 1794 was notorious for the extent to which the army suffered from remittent fever. The poison is probably manufactured in the soil of the agueish locality. It has been supposed to be associated with decaying vegetable matter, and was at one time held to be a gas. In 1879 Klebs and Tommasi Crudeli isolated from the soil of certain districts near Rome an organism, the bacillus malarise, which they hold to be the active agent in the causation of ague. The most recent view is that the vera causa of malaria is the "plasmodium malariae." a protozoon which is found in the red blood-cells of ague patients. Enlargement of the spleen is an almost constant phenomenon in attacks of ague, and in those in whom the disease assumes a chronic form some permanent increase in size of that organ may result. Various forms of neuralgia are also met with in old subjects of ague, of which "brow-ague" has received a special name.