atmosphere; the determination of a considerably more ac- 

 curate value for the ellipticity of the Earth than previously 

 available, and the indication that the surface of the Earth 

 is in fact not even a spheroid, but has unequal diameters 

 in the equatorial plane also; and the establishment of the 

 great thickness of the Antarctic ice cap, and the actual 

 distribution of land beneath the ice. 



The total eradication of malaria, which used to affect 

 350 million people in the world 15 years ago, with several 

 million deaths annually, is the aim of the World Health 

 Organization programme begun in 1957. This effort in 

 applied science, which is making use of already available 

 knowledge of malaria and its transmission by the Anophe- 

 les mosquito, is an excellent example of the enormous 

 progress which can be achieved in an international plan of 

 real importance to Mankind as a whole. 



The life-cycle of the malarial parasite, the microscopic 

 cause of the disease, is fairly complicated and includes 

 stages in both man and mosquito. When an infected human 

 is bitten by a mosquito, parasites circulating in the per- 

 son's blood are transferred to the insect, in which they 

 undergo development into a stage capable of reinfecting 

 humans. The parasite is reinjected into humans by the mos- 

 quito biting them, but between its blood meals the mos- 

 quito settles on any available vertical surface to perform 

 digestion. Consequently spraying of all wall surfaces in 

 every human habitation in malarial areas with suitable in- 

 secticides (e.g. D.D.T.), so killing the mosquito vectors, 

 breaks the transmission mechanism. In 1953 W.H.O. con- 

 trol campaigns had succeeded in protecting 6 million peo- 

 ple, but the development by several mosquito species of 

 resistance to insecticides made it evident that only world- 

 wide eradication was likely to rid Man of malaria per- 



72 



