122 



TRANSLOCATION IN PLANTS 



0.0573 per cent (220 to 573 p.p.m.)- In two out of three 

 sets of data given, the organic matter greatly exceeded the 

 inorganic. Enzymes, sugars, nitrates, and nitrites were 

 identified and it seems that the concentration and com- 

 position of this exudate are similar to those obtained from 

 bleeding vines. 



The finding of inorganic constituents and nitrogen in 

 tracheal sap seems a more serious difficulty to the accept- 



Table 17. — Inorganic Constituents in Tracheal Sap of Pear and in 



THE Soil Extract 



{From Anderssen Table I) 



ance of the phloem hypothesis than is that of finding sugar. 

 This is because, relative to the probable amounts used, the 

 inorganic content of tracheal sap seems higher than that of 

 sugar, except possibly during the periods when the sugar 

 contents are extremely high. Wormall (1924) , for example, 

 found about a third of the soUds of the sap from bleeding 

 grape vines to be inorganic material. Anderssen (1929), as 

 shown in Table 17, found appreciable quantities of inorganic 

 ions while some, in fact, were present at concentrations in 

 excess of those found in a soil extract. In Fig. 8 is pre- 

 sented a curve from Anderssen showing changes with the 

 season in conductivity of tracheal sap from pears. 



