242 PROCESS OF DEVELOPEMENT. CHAP. IV. 



which has been newly generated ? And if the cir- 

 culation is completed only by the entrance of the 

 descending fluid into the alburnum of the former 

 year, what becomes of the circulation of juices 

 during the first year of the plant's growth, when 

 there is yet no alburnum of a former year to enter ? 

 which if it does enter in future years, why is it carried 

 up again ? It does not seem necessary to complete 

 the circulation, and upon Mr. Knight's principles it 

 ought rather to remain for the purpose of effecting 

 the induration of the wood. In short there seems 

 to be a great deal of confusion and contradiction in 

 Mr. Knight's hypothesis. For first he supposes 

 that the superior specific gravity and superior 

 quality of winter felled wood depends upon a sub- 

 stance deposited in the alburnum during the pre- 

 ceeding summer and autumn, and yet he abstracts 

 the major part of it in the succeeding spring without 

 replacing it by a quantity sufficient to account for 

 its increased solidity in the subsequent winter, or at 

 least, without replacing it by any quantity which is 

 to remain permanent 

 Whose Mr. Knight's hypothesis, therefore, cannot be 



hypothesis . . 



is inde- true in its whole extent ; for if the supposed circu- 

 e * lation exists, then the superior quality of winter 

 felled wood does not ultimately depend upon any 

 substance deposited in the alburnum in summer, 

 because it is all or in great part carried off in the 

 succeeding spring and not absolutely proved to be 

 replaced in the subsequent summer; and if the 



