NA TURE 



[August 5, 1922 



of half shoes by farm-workers has reduced infection to 

 less than one-tenth of the usual rate suffered by those 

 who did not wear shoes. 



Only a few outstanding points in this valuable report 

 have been cited, but enough has been given to show 

 that in bookworm disease we have a notable illustration 

 of the close connexion between elementary sanitation 

 and the prevention of disease. In England we associate 

 this connexion chiefly with diarrhoea and enteric 

 fever, and William Budd's researches will always 

 furnish the classical illustration of the close relations 

 between defective latrine accommodation and the 

 spread of infection as soon as typhoid fever is intro- 

 duced into a village. The association is probably 

 wider than is usually suspected. The relation of 

 excessive diarrhoea to the continuance of conservancy 

 systems in English towns and villages has been re- 

 peatedly emphasised, and there is strong reason for 

 assuming a similar association of these systems with 

 excessive pneumonia in young children. 



But the hookworm story emphasises even mere the 

 importance of exact knowledge of the infecting agent. 

 The provision of shoes or even their compulsory 

 wearing is a novelty in sanitary administration from 

 a British point of view ; but it appears to be the most 

 urgent need where hookworm disease is endemic. 

 So, likewise, the fact that hookworm disease is an 

 occupational disease shows where preventive work is 

 chiefly needed, while the distinction between incidental 

 infection and actual disease points to the persons among 

 whom administrative control must be chiefly attempted. 

 These contentions are illustrated in the paper by the 

 wasted effort displayed in such public health work as 

 the " swat-the-fly " campaign, in which a vast amount 

 of effort and much money are expended in fruitless 

 endeavours to eliminate flies by wholly illogical 

 methods. 



The Vegetation of High Asia. 

 Southern Tibet : Discoveries in Former Times com- 

 pared with my own Researches in igo6-igoS. By 

 Sven Hedin. II. A List of Flowering Plants from 

 Inner Asia, collected by Dr. Sven Hedin, deter- 

 mined by various authors, and compiled by C. H. 

 Ostenfeld and Ove Paulsen. Pp. 25 + 100 + 8 plates. 

 (Stockholm : Lithographic Institute of the General 

 Staff of the Swedish Army, 1922.) 30 marks. 



KNOWLEDGE of the vegetation of High Asia is 

 now extensive. The climate, while leaving 

 something to be desired in other respects, favours the 

 preparation of botanical specimens, and travellers in 

 the inclement uplands of Tibet and the Pamirs have 

 supplied much material for herbarium use. Yet, 

 NO. 27 S3, VOL. no] 



owing to circumstances beyond their control, this 

 material compares unfavourably with that secured by 

 explorers in temperate and tropical regions. As a 

 result, our acquaintance with the flora of High Asia 

 is still far from exhaustive. 



Geographical reconnaissance involves the investiga- 

 tion of as much ground as an expedition can map, 

 and is thus somewhat incompatible with an intensive 

 study of the vegetation of a given area throughout a 

 round of the seasons. Any combination of the two 

 activities means either that geography must be content 

 with fewer data, or that botany must rest satisfied 

 with indifferent material. The best botanical results 

 of geographical expeditions are obtained during halts 

 made when plants are in active growth. 



The traveller in temperate regions may arrange his 

 halts. In the tropics, as in high latitudes and at great 

 altitudes, halts usually depend on meteorological con- 

 ditions. Those caused by heat or rain coincide with 

 periods of vegetative activity ; those due to cold and 

 snow occur when plants are dormant. The arctic- 

 alpine flowering season is, besides, so brief that when 

 the explorer sets out he may find only leaf-specimens ; 

 ere his journey ends, he may collect only specimens of 

 plants the seeds of which have fallen. He may, if 

 fortunate, secure complete material of species general 

 along his route but he must be prepared for the 

 possibility that his specimens of local plants are not 

 always identifiable. 



The botanical interest in any collection of plants 

 from High Asia is therefore intelligible. Underlying 

 this interest is a hope that new material may resolve 

 old doubts. That hope explains our attitude towards 

 arctic and alpine collections as compared with those 

 from temperate latitudes or moderate elevations. A 

 difference of a few days in the dates on which particular 

 arctic or alpine camping-grounds were visited may 

 give assurance to identifications originally tentative. 

 The value of any High Asian collection is thus enhanced 

 if it comes from districts already carefully investigated. 



The importance of a census of the flowering plants 

 found by Dr. Sven Hedin in the course of his various 

 journeys in Inner Asia during 1894-1907 will therefore 

 be readily appreciated. This census, compiled by 

 workers so careful and competent as Prof. C. H. Osten- 

 feld and Dr. 0. Paulsen, affords concrete evidence of 

 the effects upon botanical survey of the exigencies of 

 geographical exploration at great heights, and exempli- 

 fies the disadvantages against which the traveller on 

 lofty uplands must contend. 



The praiseworthy pains the authors have taken to 

 identify many incomplete specimens have been more 

 than justified by their results. Notwithstanding their 

 care, the compilers have felt debarred from suggesting 



