5IO Malaria 



with daily — quotidian — ^paroxysms, or with irregular paroxysms, or 

 the fever may be remittent. The infection is sometimes mild, but 

 may be so severe as to be rapidly fatal. In such cases the number 

 of parasites is enormous, the cerebral capillaries become filled with 

 them, and coma quickly comes on and is soon followed by death. 

 Such cases are described as "congestive chills" or "algid" cases. 



Cultivation of the Parasites. — The parasites have been successfully 

 cultivated in blood, prevented from coagulation, by Bass. 



In the first paper, Bass* announced that the cultivation of these 

 parasites was made possible by the maintenance of the culture at 

 4o°C., the selection of such an elevated temperature being based 

 upon the theory that in the bloods of infected human beings, there 

 were specific amboceptors directed against the invading organisms, 

 but unable to effect their destruction until complement is formed. 

 Complement soon appears in the drawn blood, according to Bass, 

 unless the temperature be sufficiently elevated to prevent it, and he 

 finds 4o°C. sufficient for the purpose. A later paper by Bass and 

 Johns t gives the details of cultivation as follows: 



When blood is to be taken from a malarial patient for the purpose of cultivat- 

 ing the parasites, one prepares a sterile 50 per cent, solution of Merck's dex- 

 trose, in distilled water, and measured into a sterilized test-tube, i inch in 

 diameter o. i cc. for each 10 cc. of blood to be collected. The tube, which is called 

 the "defibrinating tube" is provided with a glass rod that passes through the 

 cotton plug to the bottom of the ube. A needle is plunged into the arm vein 

 of the patient, and the infected blood is permitted to flow into the defibrinating 

 tube until the requisite quantity has been collected. The needle is then with- 

 drawn, the arm dressed, and the blood gently stirred or whipped until defibri- 

 nated. In the process of collecting and whipping, the admixture of air with the 

 blood is to be avoided. 



If only one generation of parasites is to be cultivated, the culture may be 

 grown in the defibrination tube, provided that the contained column of blood be 

 not greater than 1-2 inches. There is no advantage in having a deeper column 

 of blood, but there is danger in having less depth as under such circumstances 

 the parasites die before the stage of segmentation is reached. In case the column 

 is more than the required depth, some of the blood can be pipetted to other tubes 

 and several cultures made. The Plasmodia grow in the top layer of the sedi- 

 mented cells, near the clear supernatant serum above. The thickness of the 

 layer of cells in which they live is said to be not more than J^o of an inch. 



If the cultures are to be continued for numerous generations, precautions 

 must be taken to exempt the parasites from the destructive activities of the 

 leukocytes. The method is therefore varied in this manner: The defibrinated 

 blood is_ centrifugalized until three layers are formed, clear serum above, leu- 

 kocytes in a thin layer below, and red corpuscles at the bottom. The clear serum 

 is pipetted off and filled into small culture tubes to make a column not deeper 

 than i}i inches. Red blood-corpuscles and Plasmodia are then drawn up from 

 the deeper part of the corpuscular layer, thus escaping the leukocytes at the top, 

 and planted at the bottom of each tube of serum. It is thought to be advan- 

 tageous to use cultures tubes with flat bottoms. A still better method is the 

 introduction of a paper disk into a half-inch tube, about half an inch below the 

 surface of the serum, and then place one- or two-tenths of a cubic centimeter 

 of corpuscles upon it. Under these circumstances all of the Plasmodia are 

 said to grow and segment. Two or three generations of parasites grow in such 

 cultures, then the plasmodia begin to die out, so that if the culture is to be 

 perpetuated, they must be transplanted to freshly prepared blood-corpuscle 



* Jour. Amer. Med. Asso., 1911, lvii, 1534. 

 t "Jour. Exp. Med.," 1912, xvi, 567. 



