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This part was undertaken by Dr. Daniels, who, in 1898, proceeded to India for that purpose. He repeated Ross's experiments under his directions, and confirmed in every particular his facts and conclusions. Meanwhile, the other two members of the Com- mission were engaged in researches in British Central Africa where, for reasons which need not be detailed here, it was decided that they should begin their investigations. Daniels joined them after completing his mission to Ross, but he worked for the most part independently. Valuable observations were made by all the members of the Com- mission, but, partly for the reason that the opportunites for making observations were not so great as had been anticipated, their labours in British Central Africa, though extending our knowledge in several respects, cannot be said to have produced any very striking results. The investigations conducted there were chiefly of an introductory and preparatory character. Returning to England in 1899. Drs. Stephens sud Christophers, now fully acquainted with all the recent results obtained in India by Major Ross and in Italy by various observers, proceeded in the same year to the West Coast of Africa. Here their researches confirmed and extended our previous knowledge, and their studies on the distribution and natural history of the several species of Anopheles, and other mosquitos met with there, were of great value.
They further made the most important discovery (nade independently about the the same time by Koch) that while the native adult in such regions is in great measure immune towards malaria, the disease is exceedingly prevalent among native children. They showed, indeed, that this was so much the case that in these regions the native is a prime agent in the infection of Europeans with malaria, and that the segregation of the white man from the native, and the avoidance of native huts, which are nests of infected Anopheles, form a potent means for the prevention of the disease. The importance of this discovery from a prophylactic point of view is of the first order.
After completing their researches on the West Coast of Africa at Lagos and Sierra Leone, Drs. Stephens and Christophers proceeded in 1901 to India, carrying out their researches first in Bengal and subsequently in the Punjaub.
They have carefully investigated in various districts the species of Anopheles carry- ing the malaria parasite and acting as agents of infection, a knowledge of which is the necessary antecedent to prophylactic measures.
They find as in West Africa, though perhaps to a less extent, that the native children contain parasites in their blood and must, therefore, be regarded as sources of infection. They maintain, indeed, that in any district the percentage of native children infected with the parasite may be taken as the index of the prevalence of malaria in the district, or as they term it, of malarial endemicity; and they have determined the connection of this index with the presence or nearness of the breeding places of the species of Anopheles serving as carriers of infection. This knowledge is of direct service from a prophylactic point of view.
They point out, however, that in certain cases abundance of a species capable, if themselves infected, of infecting man, may exist with a very low malarial endemic index; this points to certain unknown factors in the spread of the disease, the discovery of which may be of great practical value.
Their study of the malaria at Mian Mir led them to begin an interesting experiment on a inethod of exterminating the infecting Anopheles by treatment of the irrigation canals. This experiment, in order to be demonstrative, needed to be carried on for a considerable time, and, since the departure of Drs. Stephens and Christophers, has been carried on by Captain James.
At the outset, the Commission was instructed to study, not only ordinary malaria in its various forms, but also.and especially the disease known as "Black-water Fever," the relations of which to malaria had been a matter of dispute, some observers maintaining that it was a form of malaria, others that it has no necessary connection with that disease, or is at any rate due to a special strain of parasite.
Drs. Stephens and Christophers began their study of Blackwater Fever in British Central Africa and continued to investigate it in the West Coast of Africa and in India. Their observations have led them to the conclusion that the disease is essentially of malarial origin and not due to a different parasite. Though, with the onset of an attack the malarial organisms disappear from the blood, they leave distinc-