378 



Scientific Proceedings^ Royal Dublin Society. 



any considerable magnitude occurred in it. With this end in view, pieces 

 were cut from the branches, at the same level on each occasion, and roots of 

 the following trees, and examined cryoscopically, electrically, and chemically : 

 Acer pseudoplaiauns, Cotoneaster frigida, Fagus silvatica. Ilex aqmfolium, 

 Populus alba, and Salix hahi/lonica. 



Under hexose and sucrose is given an approximate estimate of the amount 

 of these sugars present ; when 5 drops of the sap decolorized 10 drops of 

 boiling normal Fehling's solution xxxx are set in the hexose column, when 

 equal volumes were required xx, and when 20 drops of the sap had to be used 

 for 10 drops of Fehling's solution x is put down. Under sucrose a similar 

 notation is used, indicating the volume of sap, inverted by boiling with 

 hydrochloric acid, required to decolorize the boiling Fehling solution. 

 Allowance is made for hexose if any was found previous to inversion. In the 

 same way a barely perceptible rediiction is indicated by + and a more 

 marked trace by ++. It may be mentioned that the values of these signs 

 approximately correspond xxxx to 1 per cent., xxx to 0'75 per cent., xx to 

 O'oO per cent., and x to 0*25 per cent. ; + to O'Ol per cent., and ++ to O'l per cent. 



Where m is written in the sucrose column the presence of maltose was 

 detected by phenyl-hydrazine. Of course maltose, being a reducing sugar, 

 contributes to the precipitate observed before inversion. It is somewhat 

 hydrolysed by short boiling with acid, and consequently adds to the precipitate 

 occurring after inversion. Its presence renders tiie identification of a hexose 

 by the reduction test doubtful. 



An asterisk is placed on the date at which the leaves of the buds began to 



expand. 



Table IV. 



• Acer 2}seudopl((tanu8. Wood-sap from Stem at 25-ft. level, and from Root. 



