clxxxix 

 / 



animal possessing will struggles only in the same way. He could 

 not help feeling a little indignation at Mr. Darwin's illogical use 

 of such expressions as "natural selection," or "a law acting," as 

 if those things could do anything. A law does not act ; it is 

 merely operative by sheer obstruction and resistance. It is not 

 an active power. 



Mr. Riley defended the use of the first two expressions ; he 

 thought they were happy, and ought not to be viewed in so hy- 

 percritical a sense. Words are mere symbols to convey ideas, 

 and come'to have various meanings according as they are used by 

 high authorit}-. The terms criticized have been generally accepted 

 as expressions of the meaning Darwin gave to them. This does 

 not imply present conscious action, and " struggle for existence" 

 should no more be taken in its literal sense than "shipping a car- 

 load," or dozens of other expressions which have come to have a 

 special meaning by common acceptance and accord. 



Dr. Engelmann presented a chip from the big California tree, 

 Sequoia gigantea^ now on exhibition in this cit}', the wood of 

 which (without the bark) is represented as having a diameter of 

 25 feet. The specimen, from the external part, or latest growth 

 of the tree, showed ^^ annual rings in a thickness of 55 millime- 

 ters ; 10 rings had a thickness of 6 mm., in other pieces only of 

 4 or 5 mm ; the sapwood of this tree has a thickness of about 

 100 mm., and consists of 120 to 150 annual layers. As a general 

 rule, then, the external portions of wood proper and of sap in 

 this specimen have annual rings of \-\\ mm. in thickness, indi- 

 cating an increase in thickness of the whole tree during this latest 

 period of its existence of 1-3 mm. annually, or 4-13 inches every 

 hundred years. But in its younger years the tree grew much 

 faster, as proved by a specimen of wood said to come from the 

 innermost part of the tree, which exhibits 30 rings in a thickness 

 of 86 mm., or i ring nearly 3 mm. thick, indicating an increase 

 of 2 feet in 100 years. Whether at any time the tree grew more 

 rapidly can not be ascertained from any of the specimens ; it is, 

 therefore, not safe to base any calculations on these incomplete 

 data. They only permit us to say that at one time one foot of 

 increase was accomplished in 50 years, at a later period in 100, 

 and even in 300 years. It is well known that Dr. A. Gray, with 

 much more complete material at his disposal, accorded to this 

 species an age of about 2,000 years, more or less. 



