1. Multiple infection of red corpuscles with young parasites is seen in all malarial infections, but it is found most frequently in the æstivo-autumnal infections. The occurrence is accidental and has no significance other than that if the instances are numerous it suggests a heavy infection.
2. In instances of multiple infection the young parasites may be seen to be attached: (a) each encircling its own corpuscular mound, giving the typical ring-form picture, or (b) two or more encircling one corpuscular mound, giving the appearance of a single ring with two or more masses of chromatin.
3. Certain hypotheses as to the conjugation of malarial parasites have been formulated by observers to explain various instances of multiple infection. I do not believe that conjugation ever occurs. I believe that these hypotheses resulted from observation of certain appearances presented by the attached parasites, as when they are attached so closely together that they may appear to be adherent, or when two or more are attached to one corpuscular mound, giving the appearance of a single parasite with more than one mass of chromatin.
4. Certain appearances have also been described as a precocious division of the chromatin masses of young parasites. In these instances the chromatin granules were usually described as varying in size. Such an appearance may be explained as follows: (a) two young parasites in varying stages of development may encircle one corpuscular mound, the cytoplasm of one parasite being superimposed over that of the other parasite, giving a picture of a single ring with two unequal masses of chromatin; or (b) the variation in the size and number of the chromatin masses may be the result of traumatism, as the nuclei of young parasites are rather easily broken up.
5. Multiple infection of red corpuscles with crescentic bodies is considered rather a rare occurrence. It is always accidental, and if the instances are numerous it means a severe infection.
6. When one accepts the fact that all malarial parasites are attached to the external surface of the red corpuscles, the biological and morphological characteristics of the parasites cease to be obscure.