188 SOME RECENT BESE ARCHES IN PLANT PHYSIOLOGY 



RESEARCHES ON WOOD SAP. 



In connection with investigations on the osmotic 

 pressures and conductivity of solutions of vegetable origin, 

 Dixon and Atkins (1915, 1) found it desirable to make 

 observations on the sap drawn from the conducting tracts 

 of trees. 



With this end in view, wood taken from freshly cut 

 branches and roots of Acer pseudoplatanus in the month 

 of August was subjected to such pressure that sufficient 

 sap was yielded for the determinations. The results are 

 given in Table XLVII. 



TABLE XLVII. 

 SAP PRESSED FROM WOOD OF Acer pseudoplatanus, AUGUST, 1913. 



It may be mentioned here for the sake of comparison 

 that a 1 per cent, solution of glucose gives a depression of 

 0-106, a 1 per cent, solution of sucrose gives a depression 

 of 0-054, and a 1 per cent, solution of potassium chloride 

 gives a depression of 0'459. 



Accordingly the sap must contain 1-5 to 3 per cent, of 

 sugar at least, on the assumption that the non-electrolytes 

 are all glucose; or from 3 to 6 per cent, approximately if 

 sucrose forms the preponderating part. 



A little consideration made it clear that the liquid 

 issuing from the crushed wood must contain some sap 

 pressed from the cells of the medullary rays and of the 



