442 REPORTS ON THE STATE OF SCIENCE, ETC. 



The Eflfect of Ultra-violet Light on Plants. — Report of Committee 

 (Prof. W. Neilson Jones, Chairman ; Dr. E. M. Delp, Secretary ; 

 Prof. V. H. Blackman, F.R.S.). Drawn up by the Secretary. 



Experiments have been carried out under my direction from July 1927 to March 

 1928 at the experimental greenhouse at Bedford College, by the courtesy of Prof .Neilson 

 Jones. In June the apparatus was removed to Westfield College, but owing to the 

 alterations in the electrical supply which its installation there necessitated, its use 

 has been considerably delayed. 



Plants of Voandzeia suhterranea were subjected to short daily irradiations from 

 a Hewittic mercury vapour lamp, transmitted through selective glass screens. The 

 time of exposure under each was adjusted as far as possible so that the amount of 

 energy received in unit time under each was about equal, as judged by the visual 

 effect on standardised lithopone paint. An anatomical investigation of these 

 plants has been made. It is hoped that these experiments may be repeated and 

 confirmed, using a thermopile and galvanometer to measure the incident energy more 

 exactly. 



Previous experiments have shown that plant surfaces exposed to the unscreened 

 radiations frequently become browned, the browned areas corresponding to regions 

 where the epidermal cells are killed and have coUapsed. The epidermal coUapse 

 has been investigated in more detail, using a variety of plants. A short account of 

 these epidermal experiments is being read before Section K of the British Association 

 by Miss M. T. Martin, B.Sc. 



The accounts show an unexpended balance of £20 9s. 9d. on the last year's grant. 

 This is owing to the unexpected delays in the transference and installation of the 

 mercury vapour lamp at Westfield CoUege. The cost of an appropriate thermo- 

 pile and galvanometer will be from £50 to £60, and it is hoped that the committee 

 may be continued in office for another year, with power to use the balance in part 

 payment of these instruments. 



