972 



SCIENCE. 



[N. S. Vol. XIV. No. 364. 



proportion of blue rays. These mountain tops 

 maybe among the dryest places on the con- 

 tinent or may contain swamp pockets. There 

 is no distinct type of Alpine vegetation as 

 such ; but Alpine plants are really xerophytes, 

 being such plants as have adapted themselves 

 to an insufficient water supply. 



Our Alpine plants are often thought to be 

 identical with polar plants. But the polar 

 plant receives light continuously through a 

 long period, though the light is of little inten- 

 sity. The polar plant has an atmosphere of 

 much greater humidity, but a much colder soil. 

 Polar plants develop much greater thickness 

 of leaf. Alpine plants abound in more numer- 

 ous protective devices, as waxy coatings, hair, 

 thicker stems, and modes of propagation with- 

 out seeds. Poa alpina, for example, in many 

 mountain regions is never known to flower. 



Remarks followed regarding the viviparous 

 state of Poa alpina, Dr. Rydberg observing its 

 abundance in Greenland and Spitzbergen, and 

 Miss Isaacs remarking on her collecting it at 

 7,500 feet altitude during the last summer in 

 Switzerland. 



Dr. Underwood called attention to the rela- 

 tive amount of sunlight in tropical and in 

 northern regions, showing that the amount of 

 light is much greater north of the tropics, though 

 more oblique. 



Discussion followed regarding relations of 

 moisture. Dr. Schoeney referred to the peculiar 

 erect and densely appressed stems assumed by 

 a cespitose Opuntia about Boulder, Colorado. 

 Dr. MacDougal spoke of the remarkable degree 

 to which many of the Cacti have adapted them- 

 selves to xerophytic conditions, so that they 

 lose water less than 3^0 as readily as in or- 

 dinary plant structures in similar positions. 



Dr. Rydberg referred to the permanent moist- 

 ure found within ten or twelve inches of the 

 surface in the dry sand hills of Nebraska. 



The second paper was by Dr. P. A. Rydberg, 

 ' Revisions of Limnorchis,^ being a study now 

 printing in the Bulletin, treating of the former 

 genus Habenaria and of segregations accepted 

 from it, including the new genera Limnorchis, 

 the green and swamp orchids of the Eastern 

 United States, Piperia, Lysiella and Gymnadeni- 

 opsis; and the revival of the genus Blephari- 



glottis of Rahnesque. The first Limnorchis de- 

 scribed was Koenig's ' Orchis hyperborea,' often 

 found in Iceland and Greenland, but rare in 

 America, though sometimes occurring in the 

 cold upper region of New York and Canada. 

 Discussion of synonymy and illustration by 

 numerous specimens accompanied the paper. 

 The diagnostic characters were drawn from 

 the spur, lip and stamens, 24 species of Lim- 

 norchis and 9 of Piperia being recognized. 



Reference w^as made by Mr. G. H. Watson 

 to a remarkable growth near Ellenville, New 

 York, where two trees not only different in 

 species, but in family had so twisted together 

 as to become incorporated, and in response 

 to remarks appreciating its significance, he 

 promised further investigation and a photo- 

 graph of the trees. 



Edward S. Burgess, 



Secretary. 



SCIENCE CLUB, UNIVERSITY OF WISCONSIN. 



At the November meeting of the University 

 of Wisconsin Science Club, Professor C. S. 

 Schlicter presented a paper on ' A New Method 

 of Determining the Size and Velocity of Under- 

 ground Streams,' and A. H. Pfund discussed 

 'The Dispersion and Absorption of Selenium.' 



During the past summer Professor Schlicter 

 made preliminary tests, for the Hydrographic 

 Division of the U. S. Geological Survey, of 

 the movement of streams percolating through 

 sands and gravels beneath rivers like the Ar- 

 kansas and Platte, which^ across the semi-arid 

 plains in vi^estern Kansas and Nebraska, en- 

 tirely disappear during the months of July and 

 August. The method devised for these tests 

 was an electrical one which permitted rapid and 

 extensive surveys to be made at low expense. 

 A double row of one and one-half inch drive 

 wells was sunk across the channel of the river. 

 The upstream wells were charged with a strong 

 electrolyte, which dissolved and passed down- 

 stream with the underground water. When 

 the chemical reached the lower wells its pres- 

 ence was shown by the deflection of a needle, 

 and the rate of movement was then easily 

 calculated. The underground flowage at the 

 places tested was found to range from 3 to 15 

 feet per day, and to be fairly constant, not 



