378 



SCIENCE. 



[N. S. Vol. XII. No. 297. 



most obviously governed is temperature. Oa 

 warm days the response ranged from 0.005 to 

 0.02 volt ; on cold days it did not rise above 

 0.005, and was sometimes nil. Some tests upon 

 leaves in a warmed box gave satisfactory re- 

 sults, which may thus be summed up : The 

 normal response at 15°-20° C. is diminished or 

 abolished at low temperature (10°) augmented 

 at high temperature (30°), diminished at higher 

 temperature (50°), and abolished by boiling. 



As the month of May advanced, the iris 

 leaves, even in the warm box, became more 

 and more inert, and by the 23d inst. , when the 

 plants were mostly full grown and in flower, 

 no satisfactory leaf could be found. Leaves of 

 iris appear to give more marked response at or 

 about mid-day, than at or about 6 p. m. Tested 

 by Sach's method the leaves give no evidence 

 of starch activity during isolation. 



On the failure of the iris leaves to react, 

 other leaves were sought for which should give 

 evident differences of reaction in correlation 

 with evident differences of state. Leaves of 

 tropseolum and of mathiola gave a response to 

 light contrary in the main to the ordinary iris 

 response, viz, ' positive ' during illumination, 

 and subsequently ' negative.' In these two 

 cases leaves empty of starch acted better than 

 leaves laden with starch. Leaves of begonia 

 gave a variety of responses strongly suggestive 

 of the simultaneous action of two opposed 

 forces effecting a resultant deflection in a + 

 or — direction. Leaves of ordinary garden 

 shrubs and trees, etc., e. g., lilac, pear, almond, 

 mulberry, vine, ivy, gave no distinct response ; 

 this is possibly due to a lower average metabo- 

 lism in such leaves as compared with the ac- 

 tivity of leaves of small young plants in which 

 leaf-functions are presumably concentrated 

 within a smaller area. The petals of flowers 

 gave no distinct response, which indicates that 

 chloroplasts are essential to the reaction. 



The effect of carbon dioxide upon the iris 

 leaf was abolition of response during and 

 after passage of the gas, with subsequent aug- 

 mentation. Upon mathiola and trapseolum, 

 augmentation of response followed on applying 

 air containing 1 to 3 per 100 of carbon dioxide, 

 and prompt abolition resulted from a full stream 

 run through the leaf-chamber. On the air 



supply being kept clear of carbon dioxide there 

 was gradual abolition of response, followed by 

 gradual recovery on the re-admission of a small 

 amount of carbon dioxide. 



' Fatigue ' effects may be produced if the 

 successive illuminations (of five minutes dura- 

 tion) are repeated at short intervals (10 min- 

 utes). At intervals of one hour, successive 

 illuminations of five minutes produce approxi- 

 mately equal effects. With the leaf of mathiola, 

 periods of illumination of two minutes at in- 

 tervals of 15 minutes were used without pro- 

 voking any obvious sign of fatigue. 



SCIENCE RESEARCH SCHOLARSHIPS. 

 The Commissioners for the Exhibition of 

 1851, as we learn from the London Times, have 

 made the following appointments to Science 

 Research Scholarships for the year 1900 on the 

 recommendation of the authorities of the re- 

 spective universities and colleges. The scholar- 

 ships are of the value of £150 a year, and are 

 ordinarily tenable for two years (subject to a 

 satisfactory report at the end of the first year) 

 in any university at home or abroad, or in some 

 other institution approved of by the Commis- 

 sioners. The scholars are to devote themselves 

 exclusively to study and research in some 

 branch of science, the extension of which is 

 important to the industries of the country. A 

 limited number of the scholarships are renewed 

 for a third year where it appears that the re- 

 newal is likely to result in work of scientific 

 importance. 



Nominating Institution. 



University of Edinbuxgti . . 



University of Glasgow 



University of Aberdeen 



Yorkshire College, Leeds. . . 



University Coll., Liverpool.. 



University College, London 



Owens College, Manchester. 



Univ. Coll., Nottingham 



Univ. Coll. of South Wales 

 and Monmouthshire, Car- 

 diff 



Royal Coll. Science, Dublin. 



Queen's College, Gal way.... 



University of Toronto 



Queens University, Kings- 

 ton, Ontario 



Dalhousie University, Hali- 

 fax, Nova Scotia 



University of Sydney 



Scholar. 



Charles E. Fawsitt, B.Sc. 

 Vincent J. Blyth, M.A. 

 James Moir. M.A., B.Sc. 

 William M, Varley, B.Sc. 

 John C. W. Humfrey, B.Sc. 

 Samuel Smiles, B.Sc. 

 Norman Smith, B.Sc. 

 Lorenzo L. Lloyd. 



Alice L. Embleton, B.Sc. 

 John A. Cunningham, B.A. 

 William S. Mills, B.A. 

 John Patterson, B.A. 



William C. Baker, A.M. 



The following scholarships granted in 1898 

 and 1899 have been continued for a second year 



