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48 In preparations intended to display the flagellated body most of the slides will show numbers of spheres and several or many well-stained flagellated bodies (Figs. 3, 4, 7). Very few crescents remain untransformed. If the slips are removed and dried in from five to ten minutes after being placed on the blotting-paper cells, only crescents, ovals, and spheres will be found; if they are left for three-quarters of an hour to an hour, free microgametes and residual masses may also be found, the latter sometimes enclosed in phagocytes. Occasionally, flagellated bodies are found partially included in phagocytes. Staining with carbol-fuchsin, as above described, makes, when successful, beautiful preparations, but they do not differentiate the chromatin of the nuclear elements. To show this, some form of the Romanowsky method, preferably Leishman's or Giemsa's, must be employed.

The cultivation in vitro of the malaria parasite, long and unsuccessfully attempted, was at last (1911) effected by Bass, whose results have been fully confirmed. His method is, briefly, as follows: 10 c.c. of aseptically drawn blood from the median basilic vein of an untreated malaria patient are immediately transferred to a large test-tube containing c.c. of a 50-per-cent. solution of Merck's dextrose, The tube is fitted with a cap through which runs a glass rod, and with this the blood is gently defibrinated. The mixture is distributed into culture tubes so as to form columns of about 2 in., and then incubated at 40° C. After a time it settles into three layers—an upper ($1⁄10$ in.) of serum, an intermediate ( to in.) of red and white corpuscles, and a bottom of red corpuscles. It is only in the red corpuscles of the very thin intermediate layer that the parasites grow and multiply. They are absent from the serous or top layer, and they die in the bottom layer. By drawing off with a fine pipette a little of the middle layer the progress of the culture can be watched and subcultures started. To succeed with the latter,