Tree Measurements at San Jorge, Uruguay. 467 



June 12, 1887. — All deciduous trees leafless, except oaks 

 and Paraisos. 



August 12, 1887. — Leaves coming out on young Paraisos. 



March 12, 1888. — Leaves beginning to fall from some 

 trees. 



May 12, 1888. — EoLinias lost their leaves. 



June 12, 1888. — Paraiso leaves fell suddenly after the 

 heavy rains of 1st and 2nd. 



Sept. 12, 1888. — Tender green leaves everywhere, except 

 beech and ash. (Trees imported from England.) 



Oct. 12, 1888. — Paraiso leaf and flower very backward still. 



May 13, 1889. — Leaves almost all fallen. 



July 11, 1889. — Signs of buds filling out, especially in 

 oaks. 



October 12, 1889. — Trees all in full foliage. 



Concerning decrease of growth, I wish to include some 

 remarks on the subject made by Dr Christison, for whose 

 counsels during the compilation of the accompanying tables, 

 &c., I am greatly obliged. He says, " I think it is pretty 

 clear that these decreases must be due to failure of activity 

 in growth of wood, due to fall of the leaf, because it is 

 synchronous with it, and because there is no decrease in 

 evergreens, whose leaf-functions may be supposed to be con- 

 tinuous. Of course this, a priori, should result in stagnation 

 of growth, not in decrease ; but it is not difficult to under- 

 stand how decrease may happen. The new wood is formed 

 from the sap between the bark and the already deposited 

 wood, and that sap is in an active state of circulation, caused 

 and modified by various agencies. It is easy to understand, 

 therefore, that a distension of cells and vessels by a circulat- 

 ing fluid may be so far relaxed when the causes of it are 

 removed as to produce a shrinkage. Now the leaf plays a 

 most active part in promoting circulation." 



In these notes I have tried to confine myself to state- 

 ments as to the manner in which I have been measuring my 

 trees ; to remarks on circumstances that may or may not 

 affect tree-growth ; also to some sort of explanation as to 

 what my tables and diagrams mean, remarking upon some 

 leading features presented by them ; and have also briefly 

 remarked on the varying character of the weather at San 

 Jorge for these five years. 



