NOVEMBEK 18, 1898.] 



SCIENCE. 



697 



This represents an axial row of four cells 

 with two septa omitted. The remaining 

 septum at length breaks down, so that a 

 single cavity containing eight nuclei results. 

 The single cell of Lilium is, therefore, de- 

 rived from the four axial cells of Canna, not 

 primarilj' through the omission of any divi- 

 sions of the mother cell, but by the absence 

 of the septa. 



Studies Relative to the Perigynium of the Genus 



Carex. K. M. Wiegand. 



Three theories have been advanced as to 

 the homology of the perigynium in the 

 genus Carex. By Bentham and others it 

 was considered to be composed of two 

 united bracts. Schleiden considered it to 

 be a modified perianth ; but the most plausi- 

 ble theory is that advanced by Pax, Dyer 

 and Kunth, who emphasize the fact of its 

 close resemblance to the prophyllum of 

 other monocotyledons. In many cases the 

 secondary axis within the perigynium de- 

 velops to such an extent that several rudi- 

 mentary flowers are formed in addition to 

 the fertile one. The perigynium is, there- 

 fore, not a perianth. The position of the 

 odd carpel, which is turned toward the 

 main axis of the spike, and the develop- 

 ment of the perigynium from two posterior 

 teeth, seem to indicate that the perigynium 

 is, indeed, a modified prophyllum. 



Mapidify of Circummdation Movements in Rela- 

 tion to Temperature. E. Simons and R. E. 

 B. McKenney. 



Five species were experimented with, 

 viz. : Phaseolus vulgaris, Humuluslupulus, Con- 

 volvulus sepium, Lonieera hrachypoda and 

 mstara sinensis. Darwin also experimented 

 on these plants, but gives few exact details 

 as to temperature. The average there in 

 England is 15° or 16^ C. in spring and 20° 

 to 23° C. in summer. In this paper no ac- 

 count is taken of the relative intensity of 

 the light, although data are being gathered 

 which prove that this is an extremely im- 



portant factor. In dull cold days, with 

 temperature at 15° to 19° C. movements 

 were found to be extremely slow. The aver- 

 age optimum for best results was 28° C. In 

 Convolvulus sepium two distinct types of stem 

 were observed, a rapidly circumnutating 

 and a prostrate one showing extremely fee- 

 ble movements. In the results obtained by 

 the writers it is safe to assume that the 

 temperature was on the average 12° C. 

 higher than that worked in by Darwin, and 

 in most cases the periods of revolution are 

 very considerably shorter, but at present it 

 would be rash to say that the higher tem- 

 perature is the sole or even the main de- 

 termining factor in the more rapid move- 

 ment. Light intensity and hygrometric 

 conditions of the atmosphere have been, 

 found to cooperate also, but present indi- 

 cations are that temperature is a very im- 

 portant factor, and that an optimum as well 

 as a maximum and minimum temperature 

 exist for each species. 



General Characteristics of the Dunefiora of 

 Southeastern Virginia. Thomas H. Kear- 

 ney, Jb. 



Report of a preliminary survey of the 

 plants of the coastal plain with reference to 

 their ecological distribution. The soils, 

 heat, light and other physical conditions 

 were first described. The principal plant 

 groups were thus described with an enu- 

 meration of some of the more evident 

 adaptations by which the plants were 

 brought into harmony with the physical 

 conditions. 



Vegetation of the Wooded Fresh-ivater Swamps of 

 Southeastern Virginia. Thomas H. Kear- 

 ney, Jr. (Read by title.) 



Notes on Arctic Willows. Professor W. W. 



ROWLEE. 



The Cornell party on the Peary expedi- 

 tion of 1896 brought back an exceptionally 

 good collection of willows on which this 

 paper is based. The glaucoid and myrtilloid 



