March 9, 1922' 



NA TURE 



Z'^'h 



a note of warning. Many parents still retained the 

 impression that chemistry afforded a rapid road, if not 

 to wealth, at least to a comfortable competence, 

 and that it involved a less expensive course of prepara- 

 tion than for other professions. A keen love of the 

 subject was essential to success ; but those who were 

 attracted to chemistry should be prepared to face 

 a great deal of hard and often unattractive work, 

 and to make the very real sacrifice which a professional 

 career inevitably involved. The course of training 

 of the average chemical student was of a university 

 character and made the same demands upon the 

 financial resources of parents as that for medicine 

 and the law. 



The present position of the profession should in- 

 spire its members with feelings of pride and deep 

 satisfaction, and should stimulate them to increased 



endeavours to raise it still higher towards that 

 position of pre-eminence which it was surely destined 

 to occupy. 



There was scarcely a department of human activity 

 which was not influenced more or less profoundly by 

 the discoveries and developments of chemistry, nor 

 was there a single individual in the community whose 

 comfort had not been increased and whole daily 

 life had not been made happier — or, at least, more 

 tolerable — through the beneficent operations of 

 that science. What discoveries in chemistry the 

 future might hold, and in what way those discoveries 

 might still further modify the material life of man, 

 none could say, but it was not unlikely that if any 

 distinctive term should be applied by the historian 

 of the future to the era on which we were now enter- 

 ing, he would describe it as the " Age of Chemistry." 



Biology of Mosquitoes and the Disappearance of Malaria in Denmark. 



A N interesting memoir on the biology of Danish 

 -^^ Cuhcidae has recently been completed by Dr. C. 

 Wesenberg-Lund (Mem. Acad. Roy. Sc. et Lettres de 

 Danemark, Section des Sciences, Series 8, vol. 7, 

 No. I, 1921). Forty forest-ponds were subjected to 

 regular fortnightly exploration for some years, and 

 from them twenty-five species have been obtained, 

 twenty of which have been reared from larvae. 

 Among these are four species of Ochlerotatus known 

 from America, but not hitherto found in Europe. 

 Observations on the habits of the larvae lead the author 

 to support the general conclusion reached by other 

 recent workers that the anal gills are best developed 

 in those larvae which feed at the bottom of the water. 

 The pupae are, as every one knows, capable of move- 

 ment, but they are much more stationary than is 

 usually believed ; indeed, the author goes so far as 

 to say that usually there is no locomotion during the 

 whole of the pupal stage. An attempt has been 

 made to work out the life-history of each species of 

 C ulicine from the laying of the egg onwards, and the 

 author records many interesting observations. For 

 instance, Ochlerotatus communis was found to lay its 

 eggs singly on withered leaves or on the ground under- 

 neath these ; the eggs are hatched in midwinter or 

 early spring — many of them in April — and the 

 imagines emerge in the first half of May. Mating 

 takes place shortly afterwards, but the craving for 

 l)lood does not arise until the latter part of June. 

 ICggs are deposited upon dry bottoms from August 

 ) December, but do not hatch until they have passed 

 1 rough a period of frost. The biology of Taenio- 

 , iiynchus Richardii also presents features of sp<;cial 

 interest ; the siphon of the larva pierces the sub- 

 merged roots of aquatic plants and gains access to 

 the air in the intercellular spaces ; the siphons of 

 the pupae are brought into close apposition at their 

 tips and are inserted into submerged roots. 



In an important concluding chapter on the three 



species of Anopheles — A. plumheus, bifurcatus, and 

 maculipennis, the species found also in this country — 

 the author deals especially with the biology of A. 

 maculipennis, well known as the chief carrier of 

 malaria in Europe. He states that in Denmark this 

 species sucks blood from domestic animals — pigs, 

 cattle, horses — that it is seldom seen in the open, 

 but is found, often in incredible numbers, hanging, 

 sluggish and blood-filled, from the ceilings of pig- 

 sties, cowsheds, and stables. Only exceptionally does 

 it suck the blood of man, whereas in Mediterranean 

 countries it is an outdoor species feeding largely on 

 human blood. Dr. Wesenberg-Lund considers that 

 in Denmark A. maculipennis, which is there living 

 near the northern Umit of the range of the species, has 

 ceased to be an outdoor species sucking the blood 

 of man, and has taken to an indoor life and restricted 

 its attacks to farm animals. In his opinion, this 

 change in habits has been the main factor in the 

 disappearance of malaria, the last great epidemic of 

 which took place in Denmark in 1831. 



The change in the habits of the mosquito followed 

 an alteration in agricultural methods about a hundred 

 years ago. Whereas previously the swine had been 

 driven to the woods to feed on mast, they and other 

 farm animals were thenceforward housed. The 

 stables, etc., form so many traps which attract 

 mosquitoes by the odour and heat of the animals 

 within, and once within the stable the mosquitoes 

 find all they need until the time arrives for pairing 

 and egg-laying. Thus the connection between man 

 and A. maculipennis has been broken in Denmark, 

 and malaria was therefore bound to disappear. The 

 author remarks that if the measurements of the length 

 of this mosquito given by Meigen (1818), when the 

 species presumabty fed in the open and largely on 

 man, are correct, there has been an increase in size 

 during the intervening century-, though the species is 

 there Uving near "the northern limit of its range. 



The Unity of Anthropology. 



A- 



T the annual meeting of the Royal Anthropo- 

 logical Institute on January 24 the president, 

 Dr. W. H. R. Rivers, deUvered the presidential 

 address, taking as his subject " The Unity of Anthro- 

 pology." 



The aim of the address was to show the unity 

 which underlies the apparently diverse interests of 

 the various branches of anthropology. No student of 

 simple societies can fail to recognise this unity, for 

 the different aspects of culture which are readily 



NO. 2732, VOL. 109] 



distinguished from one another in advanced civiUsa- 

 tions are in the simple societies so intertwined and 

 interdependent that it is hopeless to understand any 

 one aspect without studying the whole. It is from 

 the students of more advanced forms of human society 

 that we need a more complete recognition of the unity 

 of anthropology. 



The unity of ethnology and archaeology was illus- 

 trated by means of recent discoveries of the Rev. 

 C. E. Fox in the Solomon Islands, where after the 



