DISTORTION OF THE MALARIAL PARASITE. AN INTERPRETATION OF "PLASMODIUM TENUE" (STEPHENS.)

1. The correct interpretation of the form described by Stephens under the name of Plasmodium tenue is as follows: It is not a new species of parasite or an ameboid form, but a parasite attached to the external surface of red corpuscles and distorted by technique. 2. Evidence against a new species of parasite is: (a) they may be found in all known malarial infections and at any stage in the development of the parasite; and (b) they show evidence of distortion. 3. Evidence against ameboid forms and in favor of parasites distorted by technique is: (a) they may be found in but one of the two cover-slips prepared simultaneously; (b) they may be found in certain definite groups in various parts of a film which otherwise contains normal appearing parasites; (c) in rich infections, containing many disforted forms, they may be found in certain parts of a film, all distorted in one direction, the infected corpuscles and those adjacent to them showing no evidence of injury; and (d) two or more parasites attached to one red corpuscle may be seen to be distorted in one direction, or to have nuclei similarly distorted. 4. Three general types of distorted parasites may be recognized: (a) parasites with nuclei distorted and cytoplasm unaltered or but slightly distorted; (b) parasites with cytoplasm distorted and nuclei intact or but little disturbed; and (c) parasites with both nuclei and cytoplasm slightly or markedly distorted. 5. Red corpuscles to which distorted parasites are attached usually appear to be flattened out with slightly irregular outline, but parasites may be more or less distorted without any apparent change in the infected corpuscle. 6. Parasites with well stained chromatin and faded cytoplasm, or parasites with well stained cytoplasm and faded chromatin, may be found in specimens containing well stained parasites. It is usually possible to restain these specimens bringing out the faded cytoplasm belonging to the well stained chromatin or the lost chromatin belonging to the well stained cytoplasm.