Carbon Assimilation. 
223 
and sucrose in two samples collected at the same time, in which the 
hexose determinations in the two cases differ by 6%. The only 
information this gives us is that there is possibly a considerable 
error due to the variability of different samples, hut two samples 
alone can give us no idea whatever of the actual magnitude of the 
probable error, which Davis and his co-workers have not determined. 
It is therefore misleading to give these two analyses under the sub¬ 
heading “ Error of Sampling.” 
In Fig. 15 are summarised the results of analyses of leaves in 
the second period. Here the hexoses are in excess of the sucrose 
Both curves show synchronising maxima at 2 p.m., 6 p.m. and 2 a.m. 
Whether these maxima have any meaning, or whether they are 
merely the result of differences in sampling, it is impossible to say. 
The fact that the hexoses and sucrose always show unusually high 
Fig. 15. Variation in Content of various Carbohydrates in the Leaf of 
Mangold during 24 hours, Sept. 10—11, 1912 (After Davis, Daish and Sawyer). 
