82 
PROPHYLAXIS OF MALARIA. 
plasmodia in this manner is simply a theory without any proof of 
scientific value, while the objection regarding the difficulty of apply¬ 
ing the method is true of many other prophylactic methods and a 
poor excuse for its neglect. Certainly in the military service, where 
men are under absolute control, there can be no excuse for neglecting 
quinine prophylaxis when it is needed, because it requires careful 
supervision and therefore entails labor upon the sanitary personel. 
Quinine prophylaxis has been found of the greatest service in keep¬ 
ing down the incidence of malaria in some of our permanent posts 
in the Philippines, and during active operations by troops in the 
field in malarial regions it will always have to be our chief defense 
against these infections. It is therefore essential that the medical 
officer be acquainted with the various methods of applying this form 
of prophylaxis, which includes a knowledge of the effect of quinine 
upon the plasmodia; the form and time of administration of the 
drug; the proper treatment of initial infections, of latent infections, 
and of gamete carriers; and, finally, of the results that may be ex¬ 
pected from this method when it is efficiently applied. 
Action of quinine upon the malarial plasmodia. —In 1807 Binz 
demonstrated that quinine in solution killed infusoria with which 
the solutions were brought in contact, and concluded from this that 
its effect in malaria was due to the destruction of the cause of the 
disease. In 1881 Laveran demonstrated that quinine solutions, when 
added to blood containing the plasmodia, produced immediate cessa¬ 
tion of the movements of the plasmodia, while Golgi, Romanowsky, 
Mannaberg, Zieman, Sehaudinn, and others described degenerative 
changes produced by the drug in the various species of plasmodia. 
The results of these various observers were often conflicting, and 
many of their conclusions were founded upon insufficient evidence. 
In 1910 1 40 published the results of continued studies upon the effect 
of quinine on the various species of plasmodia, as shown in both fresh 
and stained preparations of blood, and these results have since been 
confirmed by many obser\ r ers. They may be summarized as follows: 
Plasmodium vivax (tertian plasmodium ).—In fresh preparations 
of blood obtained after the administration of quinine marked mor¬ 
phological changes are observed in every stage of development, with 
the exception of the stage just preceding sporulation and in the 
fully-developed gametes. The morphological changes observed in 
the living organism consist in an initial stimulation of amoeboid 
activity, followed by a decrease in activity, and eventually by cessa¬ 
tion of all motion; a granular degeneration of the cytoplasm which 
has an increased refractive index; fragmentation of the plasmodium, 
followed by the apparent extrusion of the fragmented organism from 
the red corpuscle; and an apparent increase in the amount of pig¬ 
ment in those organisms which undergo development in spite of the 
