34 ANNUAL GROWTHS EECOEDED 



marked L, show the number of leaves put forth by 

 the primary axis ; and the sum of the figures of the 

 ten columns marked L, of the secondary axes, or, 

 20+15+16+21+11+13+13+13+3+2=127, shows that 

 one hundred and twenty-seven leaves were put forth by 

 the ten secondary axes or branches ; therefore, the total 

 number of leaves which constructed the entire branch, 

 was 127+28=155. 



If the reader will refer to the Table and then to the 

 Plate, he can form a true estimate as to the size of the 

 branch. The length of the primary axis is twenty-seven 

 inches and three lines, and of the largest secondary axis 

 fifteen inches : yet it is the leaf-labor of one hundred and 

 fifty-five leaves ! The branch itself we have shown to be 

 only six years old. What then must be the immense num- 

 ber of leaves engaged in the construction of trees which 

 put forth thousands of such twigs, comparatively speaking, 

 from their immense spreading branches, which grow from 

 one to two hundred feet in height, and whose giant forms 

 have stood for hundreds and even thousands of years? Who 

 can estimate the quantity of leaf-surface spread abroad in 

 the atmosphere from the first commencement of germina- 

 tion, and the amount of leaf-labor necessary to rear such 

 vast, noble, and enduring vegetable monuments ? " The 

 Washington Elm, at Cambridge, — a tree of no extraordi- 

 nary size — was some years ago estimated to produce a 

 crop of seven millions of leaves, exposing a surface of 

 two hundred thousand square feet, or about five acres of 

 foliage."* 



Again referring to the Table and the engraving, we find 

 that the increase of leaf-surface each year, was as follows : — 



1853, 5 ; 1854, 9 ; 1855, 25 ; 1856, 30 ; 1857, 41 ; 1858, 44. 

 That is to say, in 1853 the branch put forth five leaves; in 



1854, nine leaves, &c. &c. These numerical results are 

 obtained by adding together the figures under L, opposite 

 the years, across the columns. 



* " First Lessoas in Botany and Vegetable Physiology," by Asa Gray, 

 1857. 



