32 



NA TURE 



[November 8, 1900 



of light in space, it was not till 1889, so far as I can make 

 out,, that the possibility of such an extinction being 

 brought about by fine particles of matter was suggested,^ 

 and he referred, to the constitution of comets, falling 

 stars and meteorites in support of this idea. 



Now that the nebulee and stars giving us bright-lme 

 spectra, as well as comets and falling stars, have been 

 associated with meteorites, we must expect that the 

 extinction of light, if produced as suggested by Schia- 

 parelli, must very rapidly increase as the Milky Way is 

 approached. 



Hence the small magnitude stars in the Milky Way 

 are stars of which the light has been dimmed, and 

 the gap which separates system from system may be 

 gathered from Pickering's diagram (Fig. 4). 



We may perhaps, afier the recent surveys of space, 

 go a little further than Schiaparelli. A stoppage of 

 light by solid bodies, whether small meteorites or con- 

 densed stars like the sun, would affect the spectrum 

 equally from one end to the other. But we now know 

 •that many of the stars are not condensed bodies like the 

 •sun, and that in the surroundings of these, as well as in 

 the so-called gaseous nebulas, are gases and vapours 

 which would undoubtedly stop the short more than the 

 long waves of light passing through them ; and there is 

 ample evidence, as we have seen, that such stars and 

 nebulae are more numerous in the plane of the Milky 

 Way than elsewhere. If we take stars of the same 

 chemical species in and away from the Milky Way, and 

 find differences in the lengths of their spectra in the 

 ultra-violet, the inquiry would be carried one stage 

 further. 



It is a sure sign of the interest taken in such subjects 

 as these, that, since the above was written, two im- 

 portant contributions to our knowledge have appeared. 

 I hope it may be possible for me to refer to them on a 

 "future occasion. 



Norman Lockyer. 



THE MALARIA CAMPAIGN. 



DURING the last two years, no subject has been 

 more discussed in the medical world than paludism, 

 and in the discussion the general public has taken an 

 interest which purely medical matters seldom enjoy. 

 But this is not a matter of only scientific interest, as is 

 ireadily seen when one hears that five million human 

 lives are the toll India alone pays annually to the grim 

 •spectre of malaria. 



The prevention of malaria is a problem of great 

 'human, political and economic importance, and the 

 Secretary of State for the Colonies, and many wealthy 

 'individuals in London and Liverpool, have shown their 

 'recognition of this fact by great personal interest and 

 generous contributions of money for the founding of 

 ■schools of tropical medicine in these two great sea- 

 iports. 



The fact of mosquito agency in the spread of malaria 

 •suspected by many, asserted by King (now almost for- 

 ;gotten), Laveran and Manson, and subsequently proved 

 by the brilliant work of Ross, was not accepted at all 

 generally two years ago. Since then, however, expedi- 

 tions have been to various parts of the world to study 

 the whole question anew. 



Two expeditions have been sent to our colonies in 

 'West Africa by the Liverpool School of Tropical 

 Medicine, another by the Royal Society to British 

 'Central Africa, some members of which subsequently 

 followed the Liverpool men to West Africa, and lastly, 

 in May of this year, at the instance of Dr. Patrick 

 Manson, the London School of Tropical Medicine de- 

 spatched an expedition, of which more anon, to the 

 -Roman Campagna. 



1 " Sulla distribuzione apparente delle Stelle viribili ad occhio nudo." 



NO. 1619, VOL. 63] 



In addition to these special expeditions sent out from 

 home, Bignami, Celli, Grassi and other well-known 

 Italian observers have been hard at work in their own 

 country, while many medical men of our Colonial service 

 have in their own districts been on the trail of the 

 malaria parasites. 



Germany, too, as is her wont, has been equally ener- 

 getic. The great Koch, at the head of several expedi- 

 tions, has visited many parts of the world and contributed 

 largely to the sum of our present knowledge. Further- 

 more, Hamburg, the principal German seaport, has rightly 

 been chosen the seat of a school of tropical medicine, 

 whose objects are identical with those of our own schools 

 and whose head is Prof. Nocht. It is interesting to note 

 that the foundation of this school is due to the initiative 

 of the Imperial Government and the enterprise of the 

 municipal authorities of Hamburg. Save sympathy, our 

 English schools owe nothing to the Government of an 

 empire whose interests are more vitally affected by the 

 problems of tropical medicine than any other in the world. 



In the aggregate, the addition to our knowledge from 

 these various sources has been immense. The whole 

 life-history of the Haemamoebidas responsible for malaria 

 has been accurately worked out, and a particular genus 

 of mosquito (Anopheles) has been, after due trial, defi- 

 nitely convicted of carrying these parasites from man to 

 man and of acting as definitive host to the parasite 

 during its sexual phase of development. On the other 

 hand, man, the intermediate host in this cycle of alter- 

 nation of generations, has been proved equally necessary 

 for the propagation of the species. A constant associa- 

 tion therefore of man with mosquito seems the rule in a 

 vicious circle, which keeps up the supply of parasites 

 and precludes the possibility of their destruction and 

 extinction. 



One day, however, it may be shown that the human 

 Htemamoebidce can complete their asexual cycle in some 

 mammal other than man. But as yet there is no evi- 

 dence of this, and Koch has stated his disbelief in the 

 existence of any second alternative host. 



As soon as there was a fair presumption (if not positive 

 proof) that the parasites of malaria multiplied by a process 

 of alternation of generation, in which man and a mosquito 

 played the leading parts as intermediate and definitive 

 hosts respectively, all workers in the subject turned their 

 attention to the identity of the species of mosquito con- 

 cerned, their habits and bionomics, and to the best 

 method of applying practically their newly-found know- 

 ledge with a view to reducing the ravages of the fever. 



New species of Anopheles were met with, and statistics 

 of health and meteorological observations collected, with 

 the result that our knowledge of mosquito life generally, 

 and especially its relation to malaria, has greatly in- 

 creased. Major Giles, in his recent monograph on 

 " Mosquitoes," has collected and arranged many of the 

 new facts, but even now we do not know how many 

 varieties of Anopheles there are nor are we certain if all 

 species of this genus are hospitable to the malaria 

 parasites. 



In a report recently issued by the trustees of the 

 British Museum, Mr. F. V. Theobald gives us much 

 further information about the Culicidas, their distribution 

 in nature and some points to help in the identification of 

 species. From this report we learn that twenty-two 

 species of Anopheles are now known, and of these ten 

 are entirely new to science, while of Culex some ninety 

 new species have been described. 



It would appear that as a genus Anopheles is world- 

 wide in its distribution, but is more limited in regard to 

 species. This pamphlet is a valuable contribution to 

 knowledge, and is evidence of the magnitude of the work 

 now being done to increase our meagre knowledge of the 

 Culicida; and gives a good idea of the special difficulties 

 of the subject. 



