July 7, 1923] 



NA TURE 



significance of atomic number would have been missed. 

 At this stage (19 15) a general grasp had been obtained 

 of the sequence of the elements and of the essential differ- 

 ence between one atom and the next, in full agreement 

 with evidence of an entirely different type — the displace- 

 ment laws of a- and ^-particle radioactive changes. 



In the further elucidation of the organisation of the 

 satellite electrons and the interpretation of the periodic 

 table of the elements, Prof. Bohr has played the leading 

 part. The results obtained are described by Prof. 

 Bohr at length in our supplement. It is sufficient to 

 say here that, thanks to this work, we are now confident 

 that the satellite electrons are arranged in groups. 

 We know the number of electrons in each group. 

 They move about the nucleus in orbits, some of the 

 characteristics of which we already know, and these 

 characteristics are the same for all the electrons of a 

 group. We know, further, the order in which the 

 various groups appear in the system of the elements, 

 and even to a limited extent why the actual order must- 

 be observed. This information is summarised in the 

 supplement (Fig. 9). The details of the picture — im- 

 portant details — have yet to be filled in, but we can no 

 longer doubt that we are advancing on the right lines. 



In conclusion, one may glance for a moment at the 

 profound reaction of these views of atomic structure 

 on physical research. In return for their spectro- 

 scopic basis in the Balmer series, they have revolu- 

 tionised spectroscopy, which is now — X-ray and optical 

 alike — one of the main avenues of advance in physics. 

 They have created a whole new and fruitful branch of 

 study, the excitation of atoms by electronic impacts. 

 They provide a concrete picture of the atom which 

 can form, and is forming every day, a trustworthy 

 basis for the study of all branches of atomic phenomena. 

 Finally, one must expect that the facts of chemistry 

 will not much longer stand apart. Though much 

 formal progress has already been made in the theory of 

 valency, the detailed electronic theory of the structure 

 of molecules has yet to be begun : it will inevitably 

 present grave difficulties. But these views of atomic 

 structure have, for example, already presented us 

 (unasked) with a carbon atom with tetrahedral sym- 

 metr}^ ; they lead us confidently to expect that the first 

 advances in the detailed theory will not be long delayed. 



The Conquest of Malaria. 



Memoirs : With a Full Account of the Great Malaria 

 Problem and its Solntion. By Ronald Ross. Pp. 

 xi + 547 + 11 plates. (London: John Murray, 1923.) 

 245. net. 



IN Sir Ronald Ross's " Memoirs " information is to 

 be found which will interest the conventional 

 " wide circle of readers," in that the subjects treated 

 NO. 2801, VOL. 112] 



must appeal to the Imperialist, the political economist, 

 the sanitarian of the tropics, and the cosmopolitan 

 science research worker ; nor will those who respond 

 to the " call of the East " fail to find interest in details 

 of scenery and travels in India and Burma. Among 

 the items illustrating the importance of research in 

 aiding the well-being of communities and nations are 

 discussed the conditions under which the discovery 

 of the agency of malaria conveyance was made, as 

 a result of the laborious experimental efforts of the 

 author. In the section dealing with this subject 

 will be found a tale devoid of technicalities of re- 

 lentless search for a scientific truth, with its re- 

 curring disappointments, baffled schemes, renewed 

 hopes, and ultimate victory, which, in entrancing 

 interest, may compete with Sherlock Holmes's efforts 

 at his best. 



For centuries, the problem of malaria afforded a 

 favourite subject in medical writings for opinions 

 and disputations. By 1880 Laveran had found the 

 Plasmodium malaricB in the blood of human beings ; 

 but the vital matter, in respect to prevention, as to 

 how the protozoon gained entrance to man remained 

 a mystery. In 1894 Hanson excogitated an hypothesis 

 as to malaria agency, which was published in detail in 

 the Lancet (vol. i., p. 1309). Ross was in England 

 in that year. Between the younger man, eager to 

 remedy the distressing conditions arising from this 

 cause in India, and the older, glad to find an enthusiast 

 in malaria prevention, there arose a mutual professional 

 interest and interchange of views, which continued 

 during Ross's labour in that country. It has since 

 been insisted that Ross was a mere marionette under 

 the control of Manson ; indeed, that he was " selected " ^ 

 by the latter for this particular work, and that Manson 

 was the " discoverer of malaria." 



Where admiration for Manson can justly be given 

 in this matter is in contemplating his reasons for 

 framing the hypothesis of 1894, namely, that it might 

 prove an incentive to research on malaria which, as 

 he asserted {Journal of State Medicine, September 1900), 

 " is far and away the most important of the many 

 problems of tropical empire — that empire upon which 

 so much of our present and of our prospective national 

 prosperity depends." No claim to originaUty was 

 made by him, and with the one exception (added in 

 1898 to the original conjecture of 1894) that the flagella 



' This is a particularly inapt contention, seeing that before Ross " selected " 

 himself for this limitless task (p. 131, "Memoirs"), Manson had issued 

 with his hypothesis of 1894 an invitation to medical men in India generally 

 (British Medical Journal, vol. i. p. 1309) to undertake research on the lines 

 suggested, and, after Ross had furnished him with results, repeated this 

 invitation in 1896 (B.M.J. March 28). In 1898, when Ross had arrived 

 at an important stage of his discovery (B.M.J, p. 1576, 1898), Manson 

 decided " again to call the attention of workers on malaria to this promising 

 field for investigation." Further, Ross, both officially and privately, in 

 India strove to induce others independently to undertake the task. Mean- 

 while Manson did not utilise material available in England (pp. 131, 147 

 " Memoirs "). 



