The employment of malaria therapy for neurosyphilis has been decreasing since penicillin and other antibiotics appeared and neurosyphilis patients decreased recently in their number. But malaria therapy is one of the most effective therapies for neurosyphilis still now. So we must find out how to keep alive malaria blood not in vivo, simply. The results were: 1) The temperature in which malaria blood was kept, decided its fate. The preservation under 4℃, -20℃ was not suitable to keep alive malaria blood long. 2) The solution in a ratio of 4 parts of malaria blood to I part of ACD solution (anti-coagulant) was added by 1.2 to 2.5 mol. amounts of glycerin and then freezing it rapidly at a temperature of -79℃, quick thawing and injecting it intramuscularly among 65 subjects, infection was accomplished sufficiently in 54 subjects with no malaria history. The storage period was 3-242 days. Its incubation period was 12 to 28 days and the average 14.6 days. At present, the longest preservation period is 242 days. In case of slight prolongation of incubation subsequent to long preservation and the parasites figures of smears of Giemsa method, there is possibility of longer preservation than 242 days which is the longest period at this time. This method is simple, practical for malaria preservation. In this case, the factors to determine whether the blood was effectable or not effectable concerned the numbers of parasites in the blood before frozen. 3) Although the freezing drying method did not succeed this time, its possibility can be expected by observing the reconstruction of malaria parasites in glycerin using example. 4) As author described above, glycerin acts effectively on frozen-keeping of malaria protozoa, too
