The Thompsons have rather simplified the method of Bass. They draw 10 cc. of blood into a test tube containing the usual amount of glucose solution. They then defibrinate the blood by stirring with a thick wire for about five minutes and remove the wire with the adhering clot. They then pour this defibrinated blood into several small sterile test tubes, which should contain at least a one-inch column. Rubber caps are adjusted over the cotton plugs and the tubes placed in the incubator. They note the tendency of cultures of P. falciparum to agglutinate which is not true of P. vivax.
They think this agglutination the great cause of the plugging of capillaries in pernicious malaria. They note 32 merozoites as maximum number in sporulation of P. falciparum while P. vivax has usually 16 or more, but never as many as 32.
This would explain the shorter incubation period of malignant tertian. The pigment of P. falciparum clumps much earlier in the developing schizont than that of P. vivax and is much coarser and more discrete.
While Bass thought he noted parthenogenesis in cultures others have failed to observe any evidence of it.
7. Immunity.—As to immunity. There is no real immunity to malaria, it is a continuance of the infection, but the parasites are not in sufficient numbers to give rise to fever. If, however, the patient becomes chilled or fatigued or otherwise depressed, fever results.
This apparent immunity is also kept up by reinfection, because if natives leave the locality for a length of time they lose it. Patients who show this apparent immunity to one form of malaria have no such resistance to the other types. Bass states that immune bodies are produced in malaria and that immune processes contribute to control of the infection, but that it is not lasting and is not effective against new infection.
8. Perniciousness.—Causes of perniciousness. This is taken up under perniciousness in malaria. (See [page 31].)
9. Quinine-affected parasite.—Effect of quinine on malarial parasites. It is usually thought that the merozoites at the time of being thrown off from the merocyte are most vulnerable, while the gametes are only slightly affected, if at all. Still, the young forms from which gametes develop are destroyed. Quinine causes parasites to disappear from the peripheral circulation and produces degenerative changes in such parasites as may remain. Bass thinks that quinine makes the red cell permeable to the lytic action of serum. Anaemia may cause degenerative changes in parasites similar to that from quinine.
10. Anaphylaxis and the paroxysm.—Abrami has brought forward evidence in favor of the malarial paroxysm being due to the outpouring of merozoites into the blood plasma which act as foreign antigen. It is noted that the dissemination of merozoites takes place some hours before the cold stage which is one of the manifestations of anaphylactic shock. They note a leucopenia and lowering of the blood pressure preceding the paroxysm as evidence of a haemoclastic crisis.
The Anopheline Mosquito