1886-87.] Monthly Increase in Girth of Trees. 



53 



measured at intervals in February and March several trees, 

 known to be early and quick growers. The result in five 

 deciduous trees is shown in the followincr Table: — 



The movements indicated here are very trifling, not greater 

 than may be ascribed to errors of observation, unavoidable in 

 measuring large and irregular surfaces. It will also be 

 observed that the differences in excess or defect almost 

 counterbalance each other. So far as these experiments 

 go, therefore, they lend no support to the theory of early 

 spring movement, but possibly they are too limited, as the 

 following statement in Sachs' Text-Book of Botany (Eng. ed., 

 p. 728) appears to point to the occurrence of a very con- 

 siderable movement early in the season : — " The experience 

 of every year shows that the fissures in the bark, especially 

 of thick trunks, at the end of winter in February and March, 

 become deeper and wider, evidently in consequence of the 

 great swelling of the wood, which at this time contains the 

 greatest quantity of water ; while the bark had time to dry 

 up and contract during the dry weather of winter." I must 

 say, however, that the changes in the bark here described 

 have not been observed by me. 



II. Commencement of the Growing Season in Evergreen 



Trees. 



Sir Eobert Christison, from experiments on six trees, con- 

 cluded that evergreens as a class show a substantial increase 



