Concluding Remarks. i6g 



the future plant physiology will acquire the co-operation of photo- 

 chemists, who already take an interest in the work of the plant 

 physiologist. It is encouraging to find an appreciation of plant 

 physiology by the photochemist Plotnikow (1910), whose words on 

 this subject we may quote in conclusion. " Prom this one realises 

 how much material, work and patience is required for this problem. 

 But let us hope that this will prove no obstacle for further investi- 

 gations in this field. Labour loving scientists should not lose heart 

 for penetrating further along the path so far prepared. 

 A brilliant success must finally crown their labour." 



