August 27, 1886 ] 



SCIEJsrCE. 



187 



ng, and 80,000 additional slips have recently been 

 put in. At the end of two years the switches are 

 cut and made into bunches like sheaves of wheat. 

 The leaves and the bark contain the medicinal 

 , salicin. This substance crystallizes in plates, is 

 white in color, not very soluble in water, and 

 somewhat bitter to the taste. Like other bitters, 

 it promotes the appetite, and aids digestion, and 

 is regarded as an excellent tonic in some forms of 

 dyspepsia. It is also largely used in the treatment 

 of acute rheumatism, and to some extent in ma- 

 larial fevers as a substitute for quinine. It is 

 said that the willow switches, when dry, are 

 worth two hundred dollars a ton. The leaves and 

 bark are sold at the rate of twenty-five cents a 

 pound. 



— A young woman is said by a writer in the 

 Medical and surgical reporter to have acquired 

 the habit of eating roasted coffee, eating some- 

 times as much as half a pound a day, and con- 

 tinuing it for four months. She was very pale, 

 sallow, and nervous ; she had a weak pulse, im- 

 paired digestion, and got out of breath easily 

 going up stairs. 



— Professor Bystroff has recently examined 

 7,478 children in the schools of St. Petersburg, 

 and finds that 11.6 per cent suffer from headache. 

 He regards it as due to irritability of the brain, 

 brought on by the excessive forcing of the educa- 

 tion. 



— The entu'e population of Germany, as enu- 

 merated in the qiiinquennial census of December 

 last, is given at 46,840,587, an increase of 1,606,- 

 526 over that of 1880. 



— The entire length of railroads of the world, 

 up to the end of 1884, as recently published by the 

 Prussian minister of pubHc works, was 291,000 

 miles, an increase of twenty-seven per cent, or 

 over sixty thousand miles, during the preceding 

 five years. Of the entire length, very nearly one- 

 half is that of the American railroads, mainly in 

 the United States. • 



LETTERS TO THE EDITOR. 



*t*CorresiJonclents are requested to be as brief as possible. The 

 writer's name is in all cases required as proof of good faith. 



A contribution to the psychology of the polar 

 bear (Ursus maritimus Lin,). 



The fact that bears occasionally create rotary cur- 

 rents in water by means of their paws, for the pur- 

 pose of bringing floating objects within their reach, 

 has several times been verified by different observers 

 (Eomanes' ' Animal intelligence,' New York, 1883, 

 pp. 351, 352 ; Darwin's ' Descent of man,' New York, 

 1875, p. 76). Still, this act of bears has not been 

 so often recorded as to render the present instance 

 uninteresting. 



In May, 1886, happening to be in Central park, 

 New York city, I visited the bear-pit. This pit is 

 divided through the centre by a partition of iron bar^, 

 black bears being confined on one side and two polar 

 bears on the other. The water supply is furnished 

 by an oblong basin about eight feet long by four or 

 five wide, so placed that the above mentioned parti- 

 tion runs through its short axis. One of the polar 

 bears was resting on the side of the basin, opposite 

 to the front of the pit, with the side of his head snug 

 against the partition, the body being stretched out 

 alongside the margin of the basin, and his fore-paws 

 hanging over its edge. In his fore-paws he had a 

 portion of an ordinary walking-cane, about a foot and 

 a half long, and from this he evidently derived, by 

 playing with it in the water, a great deal of enjoy- 

 ment. Let this bear be known as No. 1. The other 

 bear, not being able to reach across the basin, nor to 

 reach over the head to the fore paws of No. 1, and 

 having no plaything of his own, was apparently 

 highly discomfited. This discomfiture he manifested 

 by his quick and uncertain turns around the pit, 

 ever returning to the edge of the basin or the back 

 of No. 1, there to again make an unsuccessful 

 attempt to obtain the cane. Let this bear be known 

 as No. 2. 



An interested group of spectators had now col- 

 lected, and one of them, out of sympathy for No. 2, 

 threw him a small painted stick about eight inches 

 long. This No. 2 immediately began playing with, 

 taking: it in his mouth and tossing it around in vari- 

 ous directions. Finally the little bit of wood fell into 

 the basin'of water within reach of No. 1, who hastily 

 appropriated it, much to the seeming chagrin of No. 

 2, - — this bear once more becoming very restless and 

 uneasy. The stick and the cane, however, were too 

 much for No. 1 to manage, for in his maneuvres, 

 seeming unnoticed of him, he lost his hold upon the 

 stick, and it fell into the water. At once No. 2, 

 who, at the time, was sitting on his haunches at the 

 front side of the basin, appeared to comprehend this, 

 and began pawing the water with the right and left 

 paw alternately, thus creating a current in the water 

 which brought the little piece of wood to him from 

 the other side of the basin in about two minutes. 

 Hastily taking it out of the water. No. 2 laid it on 

 the edge of the basin, for in the mean time No. 1 had 

 changed his hold on the cane in such a way that he 

 confined it between his paw and the side of the basin 

 at the water's level. His paw being at the very re- 

 mote end of the cane, thrust partly through the bars 

 into the black bear's side of the pit, the cane seemed 

 to be free upon the water. No. 2 now went through 

 the same motions as had secured him the small piece 

 of wood. After keeping his exertions up for about 

 one half-minute, he seemed to perceive that the cane 

 did not move towards him : so careening his head 

 around, he brought into full view the paw of No. 1. 

 and appeared to comprehend that the cane passed 

 between the paw of No. 1 and the basin wall, for 

 instantly he stopped pawing the water, and went to 

 playing with his own piece of wood. 



Throughout this whole scene, it seemed to me that 

 there occurred a notable change in the facial expres- 

 sion of each bear as he gained or lost a point. There 

 was no evidence of anger ; and while No. 2 was creat- 

 ing the water current, his face wore the impress of 

 the most profound earnestness, which gave way, 

 when the stick was obtained, to an expression of 

 great elation, this in turn being replaced by an in- 



