In reference to the geographic distribution, we observe that in the southern and tropical malarial regions the parasites of both the first and second group occur, though even here with a predominance of the former in the spring months, and of the latter in the second half of the year; while in northern countries the parasites of the second group and the fever associated with them occur exclusively in severe malarial regions, and then only at the height of summer. The great majority of places in northern countries show only the parasites of the first group, with their typical fever.

During my ten years' investigation of this subject I have seen not one single case of malaria with parasites of the second group, in which the infection occurred in Vienna. Cases of this kind were always introduced, usually from Hungary, Rumania, Servia, Croatia, Dalmatia, Italy, or the tropics.

Moreover, the localization of the malarial virus can be carried still further. It was noticed, even by the old clinicians, that certain types of fever, like tertian and quartan, were associated with definite places. Though this is not an absolute rule and types usually occur mixed, the fact that a geographic separation of types can occasionally be made is of considerable significance.

In this regard we have a remarkable observation from Trousseau. He says: "Le type semble bien plus tenir a la nature du miasme, et pour mieux dire, a la localite qu'il infecte, qu'a des conditions inherentes a lindividu, qui en subit les atteintes."

In support of this assertion Trousseau adds that in Tours only tertian fever occurs, and that the quartan fever observed there was always introduced and usually from Saumur, which, like Tours, lies on the left bank of the Loire. For instance, at one time 14 soldiers came to Tours from Saumur, 9 of whom, after several days, developed quartan fever. They had evidently acquired the disease in Saumur, for at the time there was exclusively tertian fever in Tours.*

I can report a similar manifestation in Vienna. In the last ten years I have seen develop here exclusively common tertian fever. The four cases of quartan which I had the opportunity of studying were all from other places. I think, therefore, that it is not unreasonable to say that, at the present time, the ordinary tertian fever with its corresponding parasite is the only one that occurs in Vienna.

These facts cannot be explained, or at most very unsatisfactorily, by the theory of polymorphism. Where can we find an analogy for the statement that a microbe would show a different form in southern and northern countries and different stages of development in spring and summer.

Laveran's assumption that the cachexia makes a nutritive soil on which the crescents can develop contradicts daily experience; for the crescents are present long before traces of the cachexia occur, and again an obstinate fever caused by parasites of the first group may lead to cachexia without a crescentic organism being seen.

All these phenomena are readily explained by the theory of multiplicity of parasites.

* In his most recent work Laveran endeavors to throw doubt on this assertion of Trousseau by quoting contrary communications from two physicians of Tours, and Saumur; yet we cannot without reason refuse to credit the absolutely definite assurance of Trousseau.

Table II.-Parasites And Types Of Fever