192 TRANSPIRATION AND ASCENT OF SAP ch. 



of the crushed leaves was examined and the osmotic 

 pressure of the original sap was calculated, allowing for 

 dilution, as before described. 



Although the determinations made on sap extracted by 

 these last two methods can only be regarded as minor 

 limits, it appears that they also have a relative signi- 

 ficance. Thus the sap yielded without treatment from 

 three samples of leaves plucked simultaneously from three 

 separate branches of Syringa vulgaris growing under 

 similar conditions had freezing-points respectively lo70, 

 1'581, and 1576. Furthermore, the increase in con- 

 centration of the sap of the parenchymatous tissues from 

 the root upwards to the leaf, which is always observable in 

 the saps extracted by the liquid-air method, is paralleled 

 by a similar gradient from below upwards in the saps 

 extracted from these tissues without treatment. 



Table 30. 

 Osmotic Pressures in Plant Organs. 



V 



No. 



of 



Expt, 



648 



;.<;;, 

 566 

 574 

 575 

 2 



3 

 520 

 533 

 528 



-.;, 



661 



5:52 



679 



11 



17 



18 



Acer pseudoplatanus leaves 



Agave amerieana ,, 



Aim' plicatile ,, ...... 



Anthumum andreanum, leaves 



,, cristallinum ,, ..... 



Catalpa bignonioides, leaves (crushed and 



diluted) .... 

 , , speciosa, leaves (crushed and diluted) 



Cerasus laurocerasus, leaves 



('haiitarrops humilis ,, 



( 'mdyline australis ,, 



Equisetum telmateia, lateral branches (un- 

 treated) 



,, ,, main stems .... 



Eucalyptus globulus, horiz. leaves .... 



,, ,, roots (untreated) . . 



Vagus silvatica var. purpurea, leaves . . . 



Fraxinus excelsior (untreated) 



,, oxyphylla, fresh leaves (untreated) 



,, ,, leaves beginning to 



wilt (untreated) . . 



Date of 

 Obs. 



26 s i:; 

 11/1/13 

 11/1 13 



27 1 L3 



27/1/13 



30/8/09 



30 8/09 



28/11/13 



29 11/13 



28 11/13 



12/9/09 



10/9/13 



29/11/12 



23/10/09 



4/10 13 



2/9/09 



11 '.Mill 



11/9/09 



A. 



207 

 840 

 292 

 623 



727 



905 : 



724 r 



522 



598' 



116 



946 



878 



970 



433 



119 



097 



230 



2 003 



P. 



14 



10 



3 



7 

 8 



22 

 20 

 18 

 19 

 13 



11 

 10 

 11 

 5 

 13 

 25 

 15 



52 

 11 

 52 

 49 

 73 



92 

 73 

 31 



22 

 43 



38 

 56 

 68 

 33 

 45 

 22 

 15 



24-09 



