December 30, 1909] 



NA TIJRE 



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ment of all that is delightful in art, useful in industry, 

 valuable lo coinmerce, and essential to existence. 



Hence the interest attaching to these publications of the 

 United Stales Geological Survey, dry (paradoxical term !), 

 statistical records for the most part, but none the less 

 engrossing in their importance, and even entertaining at 

 not infrequrnt intervals. Amid a voluminous mass of data, 

 carefully and patiently collected from day to day and year 

 to year] it is surely worthy a passing glance to note that 

 the mean annual rainfall over the United States is 

 2C1-4 inches, that the heaviest precipitation occurs upon the 

 North Pacific Coast, where, at several points in the States 

 of Washington and Oregon, it exceeds loo inches, while at 

 the back of the coastal mountain ranges the rainfall 

 diminishes rapidly southward, so that in the State of 

 Nevada it ceases altogether, or is negligibly small. From 

 another paper comes corroborative evidence on the value of 

 afTorestation, in that the data obtained clearly demonstrate 

 the fact that an increase in floods is directly associated 

 with the denudation of forest areas. -Again, it is of con- 

 siderable industrial importance to have an estimate of the 

 total available water horse-power throughout the country. 

 This is stated to lie between 200 and 250 millions, of which 

 only 5J millions have as yet been utilised. Yet again, 

 from .1 geological point of view it is instructive to learn 

 that thf whole surface of the United States is being 

 denuded at the rate of i inch in 760 years, representing 

 an annual transportation of 270 million tons of dissolved 

 matter and 513 million tons of suspended matter to tidal 

 waters. 



Rut rh'^ volumes are not merelv academicallv and 



day from some little eminence, and then stay by it till 

 help comes. If you must depend on your own exertions, 

 think carefully over all the possibilities and adopt a plan 

 of action and adhere to it." 



Excellent advice ! but it is one thing to read it amid 

 the bustle of a crowded city and another to act upon it 

 in the lonely and fearful silence of the illimitable desert. 



B. C. 



SOME RECEST WORK OX TROPICAL 

 MEDICINE. 

 'T'W'O recent numbers of the Annals of Tropical Medicine 

 ■*■ and Parasitology (vol. iii.. No. 2, October 20, and 

 No. 3, November 1) contain six memoirs, of which four 

 deal with problems relating to trypanosomes and the 

 diseases caused by them. Messrs. Kinghorn and Mont- 

 gomery discuss the important and difUcult question of the 

 flagellates found in the intestine and proboscis of tsetse- 

 flies caught wild, on the basis of observations made by 

 them during their expedition to the Zambezi, 1907-9. In 

 Glossina palpatis collected by them on Matondwi Island, at 

 the southern extremity of Lake Tanganyika, an island that 

 has been uninhabited for twenty years, they found, out of 

 1S5 flies dissected, no fewer than seventy-eight, or 42-1 per 

 cent., harbouring flagellates in the intestine, a percentage 

 which far surpasses all previous records from other places ; 

 no parasites were found, however, in the proboscis. In 

 Glossina morsitans collected near Kambole, about fifty 

 miles west of Abercorn, nine out of 113 flies examined, or 

 78 per cent., were found infected with flagellates in the 



Death Valley, looking norih toward the Black Mountains. 



Statistically interesting. They have a human side, which 

 at times is forcible in its suggestiveness. Here and there 

 are touches of the grim reality of things, allusions at once 

 startling and tragic, pictures which bring us face to face 

 with the deadly antagonism to humankind of nature in her 

 more savage aspects. Take, for instance, the pamphlet 

 entitled " Some Desert Watering Places in California and 

 Nebraska." Here are no descriptions of well-watered 

 plains and fertile valleys, but vivid sketches of an arid, 

 desolate region, comprising an area of 68,000 square miles, 

 where " the scarcity of water and the importance of a 

 knowledge of its whereabouts are indicated by the frequency' 

 with which the Press records instances of death from thirst 

 in the more remote parts of the desert." The Death Valley 

 region comprises plains which are absolute deserts, totally 

 destitute of water and treeless for a space representing 

 many days' journey. The following extract, under the 

 head of " Getting Lost," gives a vivid sketch of the possi- 

 bilities of a desert tragedy : — 



" The inexperienced traveller often gets at once into a 

 panic on losing his way, and wastes his remaining energy 

 in frantic rushes in one direction and another. This 

 tendency to become panic-stricken should be controlled, if 

 possible. Sit down, get out your map and compass — if you 

 are provided with them, as you should be — and study the 

 situation carefully before acting. .'\t least, rest a little and 

 think it over. If it is hot and you are far from camp, get 

 your head into the shade of a bush or rock, and wait till 

 night. Thirst will be less intolerable then and endurance 

 greater. If you have camp companions who are likely to 

 look for you, start a signal fire by night or a smoke by 

 NO. 20g6, VOL. 82] 



intestine, and seven out of thirty-one flies examined, or 

 21-2 per cent., were found to contain flagellates in the 

 proboscis. 



The authors give a detailed description of the parasites, 

 but, unfortunately, without any figures ; they consider that 

 the flagellates observed in G. palpalis are to be referred 

 to the type of Trypanosoma grayi, Novy, but they did 

 not observe the encystment described by Minchin. The 

 parasites observed in G. morsitans only differed slightly 

 from those observed in G. palpalis. Feeding experiments 

 were undertaken in order to trace, if possible, a develop- 

 ment of the flagellates found in G. palpalis, and with 

 rather surprising results, for while 42 per cent, of flies 

 not fed artificially contained trypanosomes, in those fed 

 only a very small proportion were found to harbour these 

 parasites. It was also found that the percentage of in- 

 testinal infections tended to decrease when flies were kept 

 in captivity, while, on the other hand, the percentage of 

 infections of the proboscis tended to increase ; but the 

 number of cases examined is scarcely sufficient to support 

 these conclusions. 



The origin of the trypanosomes occurring in " wild " 

 tsetse-flies is discussed, but without reaching very definite 

 conclusions. The authors agree with Stuhlmann that the 

 parasites in the proboscis are derived from those in the 

 intestine, and they suggest the possibility that the trypano- 

 somes tound in " wild " tsetses " may be derived from 

 pathogenic trypanosomes which lose for some unknown 

 r'-.-ison their infectivity when ingested," and also that they 

 represent a mixed infection. 



In two other memoirs the same authors report at length 



