102 TRANSLOCATION IN PLANTS 



To obtain the sap for analysis the layer of wood was cut 

 into thin shavings and extracted, but no mention is made 

 of the method of extraction. Presumably the tissues were 

 killed in this extraction, so sugars from the living cells 

 were included. Only reducing sugars were determined. 

 In a later paper (1926, p. 79) he reported other analyses 

 of sap which in these cases was evidently obtained by 

 suction from the various layers of the wood. On June 24 

 the sap from the outer layer of wood contained 0.027 per 

 cent sugar, while that from the second and third layers 

 contained 0.016 per cent. Another section of the same 

 trunk examined two days later yielded a sap of 0.02 per 

 cent sugar in the outer layer, and 0.005 per cent from the 

 second layer, 0.007 per cent from the third, and 0.006 

 per cent from the fourth. On July 2, a sample from the 

 outermost layer of a small tree showed 0.0049 per cent 

 sugar. On July 13 and 14, samples from the outer layer 

 of a small tree showed a concentration of only 0.017 per 

 cent sugar, while those from the second and third layers 

 contained 0.028 per cent to 0.030 per cent, respectively. 

 He explains the low concentration of the outer layer in 

 this instance as due to the fact that this was the outer 

 layer of recently formed internodes in which dyes move 

 up more readily than in inner layers. Five days after 

 this, the tree was cut and extractions were taken from the 

 outer layer of the lower part of the trunk. The outer 

 layer in this case contained 0.014 per cent sugar and the 

 inner layers had 0.012 per cent. In mid-August a sample 

 from the second and third layer of a small trunk showed 

 0.14 per cent sugar and one taken from a similar trunk 

 on Oct. 24 contained 0.02 per cent sugar. Though the 

 sugar contents were usually somewhat higher in the outer 

 layers than in the inner layers of wood, there were striking 

 exceptions. The differences were not great and the con- 

 centrations showed such great fluctuations that it is 

 difficult to see how this can be considered as evidence 

 for downward transfer in the outer layers. The actual 

 concentrations found were extremely low, in all but one 



