Water-Conductivity of the Wood in Trees and Shrubs. 225 



+ variation of 5, whilst 50 stems of Rhododendron ponticum taken from different 

 localities chiefly varied from 10 to 25, with a large proportion grouped about 

 18. But some were lower than 10, and a few were much higher than 25. 

 Such variation is to be expected in a plant which is so freely branched, and 

 with so wide a difference in the development of the branches, extending 

 almost from abortion to extreme luxuriance. 



Euonymns japonicus is also worth considering in this connection, and 

 especially so because it will subsequently be convenient to compare it with the 

 deciduous U. europceus. The branches of which the results are given in the 

 annexed Table were taken from four sets, of bushes, one lot growing in sandy 

 soil in Surrey, the others from good fertile garden soil in Buckinghamshire, 

 the last one growing in well-manured ground under the shade of trees. 

 Although the plant indicates considerable responsiveness to the influence of 

 the environment, it still is well within what might be called the evergreen 

 limits, and in this respect contrasts with the deciduous species. Taking the 

 mean for E. japonicus to be 12, it is seen that of 18 stems, 12 fall within 

 12 + 3, while three are above and three below these limits. 



Table IV. — Euonymus japonicus. 



Age in years. 



Absolute vol. in c.c. 

 per i hour. 



Specific vol. in c.c. 

 per i hour. 



1 



0-6 



12-5 



1 



0-5 



7-5 



1 



0-5 



10-2 



2 



1 -4 



9-0 



2 



1-0 



8-9 



1 



0-6 



9-5 



1 



0-4 



8-6 



1 



1 -4 



13-4 



2 



0-7 



11-6 



2 



0-8 



11 -3 



1 



0-8 



13 -4 



1 



0-6 



10 -9 



1 



0-3 



9-8 



2 



5-2 



19-1 



3 



4-2 



17 -0 



2 



3-9 



17-1 



3 



3 1 



14 -9 



1 



1-5 



13 -9 



Total 



218 -4 

 = 12-1 



The heaths are, as might be expected, rather low in the scale. The large 

 heath {Erica arhorea) is the highest with an average of 15 and a range of +5. 

 This may possibly be connected with ease with the lesions that often 



