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60 For this reason, and because of the easy visibility of the parasite at all its stages owing to its size and to the large amount of hæmozoin it carries, and because the entire intracorporeal cycle is completed in the peripheral blood, the quartan is the best form of malaria parasite for the beginner to study. Geographical distribution.—— The fever which the quartan parasite gives rise to—— single, double, or treble quartan ague is, relatively, much more common in temperate latitudes than in the tropics. Formerly it was common enough in England; it is still far from rare in the malarious districts of north and mid-Europe and, doubtless, elsewhere under similar climatic and telluric conditions. But as we proceed south it becomes, relatively to the other forms of malaria, rarer. In the tropics in some highly malarious places it is unknown. Thus, in a paper read at the Calcutta Medical Congress of 1894, Crombie mentioned that in his large experience he had rarely seen quartan ague. As his experience applied particularly to Calcutta and its environs, it may not hold for the whole country; in fact, Ross and others state that the quartan parasite is common enough in Madras and elsewhere in India. It is the dominating species in certain malarious districts of Ceylon and the Malay States. I have seen it in blood films from Mauritius; Ross mentions it as occurring in Sierra Leone. Doubtless it occurs in limited districts throughout the tropics. Thus, though relatively rare in many of the West India Islands, it is a common form, according to Freeman, in Antigua. The general statements that quartan ague is, relatively to the other forms of malaria, more a disease of the temperate zones than of the tropics, and, further, that both in the tropical and temperate zones it has topographically a very limited distribution, probably express the truth.

The fever.—— The ague fit in quartan is generally smart while it lasts, and well defined as regards its constituent stages (Chart 1). It does not tend so markedly, as is the case with the other malarial infections, to the rapid development of cachexia.