484 Malaria 



The macrogametocytes are broader, not curved, and sometimes 

 are ovoidal or prolate spheroidal in shape. The pigment granules 

 are more widely scattered throughout the substance. The cres- 

 cents are most numerous after the fever has lasted for some time or 

 in recurrences of the fever. 



The fever in this form of malarial infection may be intermittent 

 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 

 4oC., 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 4oC. sufficient for the purpose. A later paper by Bass and 

 Johnsj 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 tube. 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 stageof 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 %Q 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 1 3^ inches. Red blood corpuscles and plasmodia are then drawn up from 



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

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



