Grotvth and Sporulation of Tertian Malarial Parasites. 79 



stated that the parasites grew only on the surface layer of corpuscles, and 

 that no growth took place in the deeper layers. They also stated that the 

 serum destroyed the parasites when they escaped from the corpuscles, so that 

 when the spores escape they must enter immediately into a contiguous 

 corpuscle in order to survive. The hlood also, in their opinion, required to be 

 heated to a temperature of 40° C. to destroy the complement in the serum ; 

 furthermore, in order to cultivate several generations, the leucocytes had to 

 be removed. We do not believe that they have sufficient evidence for these 

 deductions. We find that the parasites develop even in the very deepest 

 layer of the column of corpuscles. Also it seems rather a contradiction that 

 the parasites should grow best on the surface layer of corpuscles, next to the 

 serum and the leucocytes which are supposed to destroy them. Xo doubt 

 the leucocytes ingest some of the parasites, but they are never able to ingest 

 all of them. Again, in one of our most successful cultures the temperature 

 of the blood never exceeded 38° C, and we have found that they are able to 

 grow at a temperature as low as 36° C. This is rather against the theory 

 of complement destruction. In an able paper by Mary Eowley Lawson 

 (1913), considerable evidence is brought forward to show that the parasites 

 are extra-corpuscular during their entire development. If this is true, then 

 the parasites would be constantly in contact with the serum which is 

 supposed to destroy them. It appears to us that the only conditions 

 necessary for the successful cultivation of the parasites are fresh corpuscles, 

 fresh serum, a temperature of 37° to 41° C. and the requisite amount of 

 glucose. The presence of leucocytes and complement is apparently 

 immaterial . 



The Optimum Temperature. — In our opinion the optimum temperature for 

 cultivation is about 38° C. On two occasions we incubated identical culture 

 tubes from the same patient, some at 37° C. and some at 41° C. On both the 

 occasions the parasites developed much more successfully in the tubes 

 incubated at 37° C. 



Haemolysis in the Culture Tubes. 



This is a rare occurrence, having been seen only once out of 15 cases. A 

 kind of haemolysis occurs after the blood has remained in the incubator for 

 several days. The corpuscles degenerate into a brownish debris, and the 

 serum shows a brown discoloration. 



Clu mping of the Malignant Tertian Parasites. 



This phenomenon has been observed in all our malignant tertian cultures 

 (12 cases). It occurs even when the parasites are scarce. It is best 



