Dec. 20 ,1915 
Mineral Composition of Sap , Leaves , and Stems 
54i 
sap flow than at the beginning. This has also been proved for two 
seasons. 
(3) The widest variations in the composition of this sap were found 
when it was collected at the same point on a main branch of the vine at 
the beginning of the sap flow during four successive years. The periodic 
loss of sap greatly weakened this branch, and there was also a steady 
decline in the mineral components of the sap taken from it, particularly 
potassium and phosphorus. 
(4) There was found a considerable variation occurring daily in the 
composition of this sap. The mineral constituents were generally higher 
during the day and the sap had a more uniform composition during the 
night. 
(5) The young leaves and stems of this vine at the same stage of growth 
were also found to vary considerably in composition during different 
years and also in the same season. 
(6) The sap of the same sugar-maple tree was found to vary widely 
in composition when collected at the same point on the tree during two 
successive years just after the sap flow had commenced. 
(7) The mineral composition of the sap of the water-maple tree was 
found to be different from that of the sugar maple. 
(8) The ratios of calcium oxid to magnesium oxid and potassium oxid 
to sodium oxid, together with other factors, demonstrate that the differ¬ 
ences in composition can not be altogether explained as being due to a 
dilution of the sap from the water in the soil. 
(9) It has been shown that the sap has a variable mineral composition 
which influences the structure of the growing parts and undoubtedly 
explains the differences in composition of the same and different varieties 
of plants. 
LITERATURE CITED 
(1) Chandler, W. H. 
1914. Sap studies with horticultural plants. Mo. Agr. Exp. Sta. Research Bui. 
14, p. 489 - 55 2 > 13 pl- Bibliography, p. 535-539. 
(2) Dixon, H. H. 
1914. Changes produced in the sap by the heating of branches. In Sci. Proc. 
Roy. Dublin Soc., n. s. v. 14, no. 15, p. 224-228. 
( 3 ) - 
1914. Transpiration and the Ascent of Sap in Plants. . . 216 p., illus. Lon¬ 
don. 
(4) -and Atkins, W. R. G. 
1910. On osmotic pressure in plants; and on a thermo-electric method of deter¬ 
mining freezing points. In Sci. Proc. Roy. Dublin Soc., n. s. v. 12, 
no. 25, p. 275-311, 2 fig. 
(5) - 
1912. Variations in the osmotic pressure of the sap of Ilex aquifolium. In Sci. 
Proc. Roy. Dublin Soc., n. s. v. 13, no. 18, p. 229-238, 2 fig. 
(6) - 
1912. Variations in the osmotic pressure of the sap of the leaves of Hedera helix. 
In Sci. Proc. Roy. Dublin Soc., n. s. v. 13, no. 19, p. 239-246, 1 fig. 
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