August 31, 1900.] 



SCIENCE. 



349 



citizens have gone out from the mayor's office 

 asking them to be present. Is it permanent 

 pavements, or leakage from gas mains, or in- 

 duction currents from the trolley wires, or the 

 elm-tree beetle that killed the elms ? these are 

 the propositions to be discussed. In view of the 

 fact that one-third of the elms on the Central 

 Green are dead or dying, the matter is of great 

 importance. 



The San Jose scale has appeared in Brooklyn 

 in many places, and it is feared that the insects 

 may do much damage to fruit and shade trees. 



The three surviving buffaloes of the Chey- 

 enne Eiver herd have been sent to Chicago, 

 where they will be sold and perhaps slaught- 

 ered. It will be remembered that an attempt 

 was made to continue the herd at Pierre, S. D. , 

 but without success. 



The government of Chile has assigned a sum 

 of $20,000 to the president of the National So- 

 ciety of Agriculture to enable him to purchase 

 agricultural machinery in foreign markets and 

 sell it at cost price to members of the Society. 



A Reutbe telegram from Liverpool says : 

 The second malarial expedition of the Liver- 

 pool School of Tropical Medicine has just wired 

 home from Bonny, in Nigeria, news of a most 

 important discovery, viz, that the parasite 

 which causes elephantiasis has, like that which 

 causes malaria, been found in the proboscis of 

 the mosquito. Oddly enough, the same dis- 

 covery has just been simultaneously made by 

 Dr. Low in England in mosquitoes brought 

 from Australia, and by Captain James in India. 

 Elephantiasis is a disease which causes hideous 

 deformity in thousands, or rather millions, of 

 natives in tropical countries, and sometimies in 

 European residents. It is due to a small worm 

 which lives in the lymphatic vessels and oc- 

 cludes them. The fact that this worm can live 

 also in the mosquito has long been known, but 

 the discovery of it in the insect's proboscis 

 shows that it enters the human body by the 

 bites of these pests. Europeans in the tropics 

 are indebted to mosquitoes not only for much 

 discomfort but for two dreadful maladies — 

 malaria and elephantiasis ; and it is high time 

 that the authorities should begin seriously to 

 consider Major Ross's advice to destroy these 



insects or their breeding-places wherever prac- 

 ticable. 



During the present summer Professor F. E. 

 Nipher, of Washington University, has been 

 working on his methods of developing positive 

 photographs in the light. The work has been 

 done in the rooms of Professor Calvin. He 

 finds that as the camera exposure is made 

 shorter, the developing band must be more 

 strongly illuminated. He is now developing 

 clear pictures, with no trace of fog when the 

 bath is placed in the direct sunlight, but cov- 

 ered by transparent color screens. Good results 

 have been obtained with ruby, and with pure 

 yellow screens. The screens are made by fix- 

 ing an unused photographic plate, and after 

 drying the gelatin film, the plate is put in a 

 water solution of red or yellow analine. 



It is said that the returns of the census in- 

 dicate a population of the United States of 

 about 75,000,000. The cities already counted 

 show the following results, the returns for this 

 year being placed beside those of 1890, with 

 the percentage of increase : 



Percentage 

 of 

 Cities. 1900. 1890. increase. 



Greater New York... 3,437,202 2,492,591 37.90 



Chicago 1,698,575 1,099,850 54.44 



Philadelpliia 1,293,697 1,046,964 23.57 



Cleveland 381,768 261,355 46.07 



Buffalo 352, 219 255, 664 37. 77 



Cincinnati 325,902 296,908 9.77 



Milwaukee 285,315 204,486 39.54 



Washington 278,718 230,392 20.98 



Jersey City 206,433 163,003 26.64 



Louisville 204,731 161,129 27.06 



Minneapolis 202,718 164,738 23.05 



Providence 175,597 132,146 32.88 



St. Paul 163,632 133,156 22.89 



Toledo 131,822 81,434 61.88 



Columbus 125,560 88,150 42.44 



Omaha 102,555 140,425 —26.98 



Hoboken 59,364 43,648 36.01 



The fifth part of Professor William H. Dall's 

 important work on the Tertiary Fauna of Flor- 

 ida, forming the fifth part of Vol. III. of the 

 Transactions of the Wagner Free Institute of 

 Science, will probably appear in September. 



Messrs. Heney Holt & Co. 's preliminary 

 fall announcement includes 'An Agricultural 

 Botany' (theoretical and practical), by Professor 



