For the treatment of general paralysis of the insane by induced malaria, the Board of Control, in consultation with the Ministry of Health, decided, at the end of 1924, to make an official arrange ment by which a pure strain of the benign tertian malaria parasite would be cultivated in mosquitoes, and would be made available for inoculation by mosquito-bites instead of by the direct inocula tion of blood from other patients. In consultation with the Mental Hospitals Department of the London County Council, the Horton Mental Hospital was selected for the work of pre paring and maintaining the strain of malaria in mosquitpes, and Col. J. R. Lord, C.B.E., Medical Superintendent of the Hospital, undertook the necessary arrangements in collaboration with Col. S. P. James, of the Medical Staff of the Ministry of Health. An isolated villa in the hospital grounds was selected as a treatment-block and laboratory; the Horton Mental Hospital authorities caused it to be mosquito-proofed and furnished, and the Ministry of Health supplied the scientific equipment of the laboratory. The Ministry also arranged that the routine laboratory work should be done by one of their laboratory assistants, Mr. P. G. Shute, under Col. James's supervision. I undertook the selection of cases suitable for treatment and their clinical care and management. The arrange ments were completed in April, 1925, and since that month 33 batches of infected mosquitoes have been prepared and utilized for the inoculation of more than 300 patients in 69 hospitals in England, Wales and Scotland.