426 Variation of Water in Trees and Shrubs, [May, 
as have come to our notice, and see how far they indicate a gen- 
eral law. 
Theoretical considerations lead us to infer that if there is any 
variation at all, the hydration of structure must be greatest during 
the period of active growth, and least during the period of rest. 
How far this is supported by the facts will appear in what 
follows. 
HYDRATION OF DEAD Woop. 
Incidentally to the main question, specimens of dead wood, 
deprived of the bark and representing an age of from four to 
eight years, were collected and the moisture determined. While 
the branches were dead, none of them were in an advanced state 
of decay, so that the contained water could not be regarded as 
that of active decomposition, but simply that which would be 
readily retained in the lifeless, air-dried substance as exposed on 
the tree. The results obtained from fifteen species of trees 
showed an extreme variation of 6.1. per cent, the range being 
from 12.9 per cent to 19.0 per cent of water. The mean hydra- 
tion obtained from these determinations was 15.1 per cent. The 
results appear in the following table : 
HYDRATION OF DEAD WOOD. 
Determined at 100° C. 
Oe a ae 
Species. Per cent of water. 
Pe en 
Acer saccharinum.... 18.8 
Amelanchier canadensis . 19.0 
Betula alba , 15.1 
« rinteet. 15.9 
“` lenta. 13.7 
Carpinus americana. ...... 13.8 
vast vesca ; : 14.0 
_ Cydoni $. 12.9 
Cornus sericea ...... 13.6 
Pinus strobus, 4 11.9 
Pyrus malus....... ; 12.9 
Prunus sate iar cues Sa ei osii Vie ee ues 14 
Quer 15.5 
Fouga canadensis 22" : ie ee oa, 18.6 
E a A E N A RES 13-5 
OER ia ee i oh E e R PCN e pee es coed 15.1 
