246 



Scientific Proceedings, Royal Dublin Society. 



Table V. 



Hedern Helix : Leaves. 



Table VI. 

 Hedem Helix : Leaves. 



In Table VI are records of the cryoscopic rise taking place in two samples 

 of sap pressed from their leaves, and stored in the dark in a closed test-tube. 



Eeference to Table III and the graph in fig. 1 will show tliat the higliest 

 figures for the freezing-point depression in winter coincide with frosty 

 weather. On these occasions we may conclude that the raising factors of 

 photosynthesis, or solution, or both, wei-e active, while the cold completely or 

 partially inhibited respiration and translocation from reducing the concentra- 

 tion. This seems the only instance of external conditions producing a well- 

 defined effect on the seasonal curve of the cryoscopic values of the sap of 

 Hedera. 



