For a long time the endeavor has been made to prevent malaria by the use of quinin, and numerous are the expressions of opinion in regard to the results. The majority contend that a systematic continued employment of quinin diminishes the number and severity of the cases; for instance, Bryson, van Buren, Jilek, Gestin, Thorel, Bizardel, Groeser, Laveran, Vallin, Saint-Macary, and others. Among the opposition we may mention Le Roy, Navarre, Reynaud.

The conviction is at present quite general that quinin is a preventive, and occasionally German, French, and English troops in malarial regions come out morning or evening, or both, for the "quinin parade," but it is rarely that this parade is carried out with strict supervision, and all kinds of expedients are adopted to avoid the bitter draft.

For instance, Jilek reported the following experiments from Pola: Among 736 men, 500 were given about 0.17 quinin pro die, in a glass of rum, from June 1 to September 20. Among these, 18.2 per cent, fell ill; of the others, 28.8 per cent. A number of instructive examples are presented in Bizarclel's thesis.

Quinin appears to act prophylactically by destroying the parasites that gain entrance to the blood or by hindering their development. In other words, the parasites find in the blood conditions unfavorable to their existence. Bearing this in mind, it is evident that little or nothing could be accomplished with doses of 0.10 to 0.20 pro die. We, therefore, agree with Laveran that the smallest daily dose worth giving is 0.50. In order to avoid, as far as possible, the disturbances caused by the quinin, the evening hours are to be preferred for administration. A dose of 0.5 should be taken at least every second evening, in powder form, in solution, or in pills.

This precautionary measure is recommended to every one who finds himself in a malarial region at the time of an endemic. It should be continued several days after leaving the region in order to destroy any organism still remaining.

The prophylaxis by means of arsenic possesses only isolated defenders, as Tommasi-Crudeli and Gouvea, and the results of others are so little encouraging that the method cannot be recommended.

Prophylaxis by means of respirators is now of historic interest only. The idea of freeing the inspired air from germs is an old one. Lancisi recommended the washing of the nasal cavities, forehead, and ears with spirits of camphor and rose vinegar, and the constant retention before the nose of a small sponge moistened with acetum theriacale. He likewise warned against swallowing the saliva, since it might be contaminated by inspired germs. The wearing of masks in which a layer of cotton filters the inspired air was recommended by Heurot and Zemanek.

Attempts at immunization were made by Celli and Santori by injecting six healthy persons with the blood serum of a buffalo, a goat, and a horse, from the region of the Pontine marshes. After 130 c.c. of serum had been injected, Celli and Santori inoculated three of the persons with blood from a patient with quartan fever, and three with blood from a severe estivo autumnal case. The serum injections were continued in some, in others not. The three persons who were injected with the blood of the estivo autumnal case were attacked within thirty hours, six and seventeen days respectively, while those injected with the blood from the quartan case manifested the disease in about twenty five days. Since considerable quantities of blood were injected (1.5 to 4 c.c), the incubation was much longer than is usually the case in persons not treated with the serum. (See Table I, p. 56.)

These investigators also inoculated a family of five persons living in a severe malarial region : three of the persons remained unaffected; one manifested a light attack, and one a relapse of an old infection. Though the experiments so far have given no satisfactory results, their continuation is desirable.

[It may be well to deal briefly here with the question of prophylaxis, which has assumed a somewhat different aspect, since our efforts are now directed by an exact scientific knowledge of the part played by anophelines in the transmission of malaria . Though our knowledge is based on universally accepted data, yet even now it is true that in the main the method of prophylaxis is the same, or at least not very different, from that practised for many a generation, viz., drainage of the soil. The only difference lies in the fact that our efforts are now directed toward eradicating or avoiding malarial mosquitos, while in the past they were directed toward eradicating or avoiding the "miasm" in the soil. It concerns the practical sanitarian or the hygienist, rather than the physician, to discover and carry out the best means of fighting the malarial mosquito. We would here indicate only some aspects of the problem, which are treated more fully in the appendix to this article, p. 206.

(1) Of mosquitos, it is only those of the subfamily Anophelince that transmit malaria , and even now we do not know if all of these, over 80 in number, do so. In fact, we can say this certainly of hardly ten. This lamentable gap in our knowledge will, no doubt, be soon filled up, but it at present exists.

(2) Other mosquitos, e. g., those of the subfamily Culicina, Aedeo myina, etc., are quite incapable of transmitting malaria . It is true, moreover, that the breeding places of these mosquitos are different from those of malarial mosquitos. Mosquitos of the genus Culex, Stegomyia, etc., breed in artificial collections of water about houses, such as water butts, old tins, etc. It is necessary, therefore, in prosecuting a campaign against mosquitos, to bear in mind these facts, because a diminution in these latter is more easily brought about, and it is not sufficient to state that mosquitos have been diminished as the result of operations (drainage, emptying of water butts, petrolage, etc.) without clearly ascertaining whether the malarial mosquitos have been influenced. Of course, the sanitarian may attack mosquitos as a whole, and not consider the species present at all, but we do not think that a blind campaign of this sort is likely in the end to be most effective. Further, on the point of economy it may be doubted whether this is advisable, for evidence exists that not all even of the Anophelince are concerned in the transmission of malaria (see page 115). The methods by which mosquitos are attacked we cannot consider in detail here. They practically resolve themselves into-(1) Drainage, i.e., doing away as far as possible with all breeding grounds; and (2) petrolage (as a temporary measure), i. e., treating the breeding places with tar, kerosene oil, or other larvicide. These methods are for the consideration of the sanitarian, and practically resolve themselves into a question of the money necessary to do away with small collections of water. We would only point out the difficulties attending the method where the water is that of an irrigation channel or flowing river with shallow, weedy banks, or where, again, at one period of the year a river is a raging torrent, at another a sandy bed with innumerable separate collections of water in which myriads of larvae occur, or again, where we have to deal with irrigated crops. We would, in conclusion, point out a means of prophylaxis carefully studied and earnestly recommended by Stephens and Christophers as the result of their close observation in tropical Africa and India. It is, in a word, "segregation." This method was designed to save the Europeans living in the deadly conditions of West Africa from the certain infection with malaria that must otherwise ensue sooner or later. As has been stated on page 208, it is the native that is the great source of malaria in the tropics. The native children are almost universally infected, and the European living in their midst is then infected by the anoph elines, which occur in thousands in native dwellings. Now, it is very striking that where in West Africa Europeans live in bungalows well isolated from native dwellings (even a quarter of a mile away), they enjoy a marked freedom from fever compared with those who live with natives in native huts at their door. The official quarters at Accra (Gold Coast), and the recently constructed hill station for Europeans at Freetown (Sierra Leone), are a striking instance of the benefits of " segregation." It was well known at Accra before the mosquito cycle was discovered that this was the healthy quarter. Here the isolated bungalows are situated some a quarter, some a half, mile from any native village, and the result is in all respects excellent. The building of European quarters, the placing of an isolated colonist's bungalow away from the immediate vicinity of villages, is a policy which must be accompanied with a striking improvement in health, and many a valuable life be rescued. Such a policy can in many instances be effected with but little cost, and should, we believe, be adopted when drainage, which is expensive and which may not be carried out for years, is being waited for. By small alterations, often implying the destruction or removal of only a few native dwellings, we are convincedvmany a European life will be spared. It is a policy that, in its highest development, is almost universal in India, where the state of civilization and progress is far beyond that of tropical Africa; it consists in the existence of a European cantonment and a separate native bazaar, and be it merely a coincidence or not, the two main centers of blackwater fever in India are just those where these conditions do not prevail, but where the tea planter or missionary is living surrounded by natives in whom endemic malaria exists to the extent of about 80 per cent. This policy, we have seen, is to benefit the European. It is justifiable on the ground that it is in the European that fever shows those pernicious and deadly effects to which so many lives are sacrificed in tropical Africa. The aim of prophylaxis in the end is to benefit the population at large, but in the tropics, where we have comparatively few Europeans living in the midst of a native community by which they are infected with malaria in its most deadly forms, it is surely in no selfish spirit of opportunism, but in a strictly justifiable spirit of self preservation, instead of reckless exposure to known evils, that some measure of segregation should be adopted. We need only point out finally that segregation is equally applicable to the colonist isolated in some remote village, to larger settlements, such as mining and railway camps, and eventually to towns, for in towns, even small ones, we find that areas actually do exist which are free from anophelines, while the suburbs of such towns may be teeming with them.

With regard to mechanical prophylaxis by wire gauze, many examples have shown that efficient protection may be obtained in this way, but the fact should not be lost sight of that such measures can be only temporary.

We may add one word with regard to personal prophylaxis. The mosquito net is absolutely indispensable, but if used in such a way that an anopheline is ever found inside, it indicates either a want of care or a want of intelligence on the part of the owner. It is possible to use a net in such a way that one may live with absolute impunity in the most highly infected regions. Finally, such adjuvants as thick clothing, gaiters, or mosquito boots for the legs and ankles are by no means to be despised. In a word, it is not too much to assert that the person who allows himself to contract malaria in the tropics is lacking in knowledge or intelligence.-Ed.]