618 



SCIENCE 



[N. S. Vol. XLV. No. 1172 



Measurement of light from artificial sources 

 has been done chiefly by photometric meth- 

 ods, but it is to be pointed out that the re- 

 sults obtained in this manner are scarcely 

 more adequate than those of the pyrheliometer. 



The sodium cell connected with a suitable 

 portable galvanometer oSers many advantages 

 for the measurement of light intensities in 

 natural habitats, and a comparison should be 

 made between it and the various photometers 

 and illuminometers which are now being rec- 

 ommended to the forestry student and the 

 ecologist. It seems highly probable that more 

 exact measurements in the blue-violet region 

 so important in photolysis and phototropism 

 will yield information by which some of the 

 current discordant results may be harmonized. 

 In any case the action of the photoelectric cell 

 in light is more nearly parallel to that of the 

 organism than that of any other light meas- 

 uring instruments hitherto available. 



"We are indebted to Professor Jacob Kimz, 

 of the University of Illinois, who has very 

 kindly constructed some cells to meet our par- 

 ticular needs and whose advice has been most 

 helpful in the application of this instrument 

 to physiological uses. 



D. T. MacDougal, 

 H. A. Spoehr 



Desert Laboratobt, 



Tucson, Arizona, 



March 30, 1917 



SOCIETIES AND ACADEMIES 



THE BIOLOGICAL SOCIETY OF WASHINGTON 



The 569th regular meeting of the society wa« 

 held in the Assembly Hall of the Cosmos Club, 

 Saturday, April 7, 1917, called to order at 8 p.m. 

 by President Hay with 45 persons in attendance. 



Under the heading brief notes and exhibition of 

 specimens Dr. B. W. Shufeldt exhibited lantern 

 slides of Uving California quail, calling attention 

 to their rapidly diminishing numbers. Dr. L. O. 

 Howard called attention to the cocoon of a Cecropia 

 moth containing moon-stones that had lately coma 

 to his notice. He expressed the opinion that they 

 had been placed there by a thieving crow or blue- 

 jay. Mr. A. Wetmore stated in this connection 

 that he had seen bluejays insert small acorns and 

 kernels of corn into large cocoons. 



The regular program consisted of two communi- 

 cations : 

 A Note on the Hibernation of the Mud-turtle: 



Alexander Wetmore and Francis Harper. 



The authors reported finding a specimen of 

 Kinosternon pennsylvanicum shortly after it had 

 left its underground winter-quarters. The hole 

 from which it had emerged was beneath a dense 

 growth of green-briar in an old field and about 

 fifty yards from the nearest marsh. The biurow 

 was 9 J inches deep, and was open save at the 

 lower end, where the animal had apparently lain 

 encased in a mass of mud. The actions and condi- 

 tions of the turtle after being placed in water 

 were described in detail, and an account of a post- 

 mortem examination of the viscera was given. 

 Messrs. W. P. Hay, M. W. Lyon, Jr., and Wm. 

 Palmer took part in the discussion. 



Botanizing in the Hawaiian Islands: A. S. Hitch- 

 cock. 



The speaker visited the Hawaiian Islands during 

 five months of 1917. He said the trade winds de- 

 posit their moisture upon the eastern and northern 

 mountains of all the islands, furnishing the condi- 

 tions for rain forests in these regions. The lee 

 side of the islands is dry even to aridity. An ija- 

 teresting feature of the wet areas at or near the 

 summit of the ridges are the open bogs. These 

 bogs are devoid of trees and large shrubs, but con- 

 tain a variety of low shrubs and herbaceous 

 plants. Many species form tussocks, or hemispheri- 

 cal masses raised above the level of the bog. The 

 most conspicuous of the tussocks is made by a 

 sedge {Oreobolus furcatus Mann.). Three peculiar 

 species of Panicum are tussock-formers {Fanicum 

 monticola Hillebr., P. imhricatum Hillebr. and P. 

 isaclmoides Munro). Owing to the extreme isola- 

 tion of the islands the flora is peculiar and interest- 

 ing. The family Lobeliacete is represented by 

 about 100 species, belonging to about 6 genera. 

 Many species are arboreous, forming trunks ten to 

 twenty feet, or in a few cases as much as forty 

 feet high. The crown of foliage gives the aspect 

 of a palm. The grasses, disregarding the intro- 

 duced species, are not numerous, but several are 

 peculiar. The genus Eragrostis is represented by 

 numerous species. A rare species of Poa (Poa 

 siphonoglossa Hack.) produces leafless rushlike 

 stems, as much as fifteen feet long. His talk was 

 illustrated by maps, botanical specimens and nu- 

 merous lantern-slide views of various features of 

 the islands. 



M. W. Lyon, Jr., 

 Recording Secretary 



