36 PROSERPINA. 



any tree in May. Weigh them ; and then consider that so 

 much weight has been added to every such living branch, 

 everywhere, this side the equator, within the last two months. 

 What is all that made of ? 



12. Well, this much the botanists really know, and tell us, 



It is made chiefly of the breath of animals ; that is to say, 



of the substance which, during the past year, animals have 

 breathed into the air ; and which, if they went on breathing, 

 and their breath were not made into trees, would poison 

 them, or rather suffocate them, as people are suffocated ii>. 

 uncleansed pits, and dogs in the Grotta del Cane. So that 

 you may look upon the grass and forests of the earth as a 

 kind of green hoar-frost, frozen upon it from our breath, as, 

 on the window-panes, the white arborescence of ice. 



13. But how is it made into wood ? 



The substances that have been breathed into the air are 

 charcoal, with oxygen and hydrogen, or, more plainly, char- 

 coal and water. Some necessary earths, in smaller quantity, 

 but absolutely essential, the trees get from the ground ; 

 but, I believe all the charcoal they want, and most of the 

 water, from the air. Now the question is, where and how do 

 they take it in, and digest it into wood ? 



14. You know, in spring, and partly through all the year, 

 except in frost, a liquid called ' sap ' circulates in trees, of 

 which the nature, one should have thought, might have been 

 ascertained by mankind in the six thousand years they have 

 been cutting wood. Under the impression always that it had 

 been ascertained, and that I could at any time know all about 

 it, I have put off till to-day, 19th October, 1869, when I am 

 past fifty, the knowing anything about it at all. But I will 

 really endeavour now to ascertain something, and take to my 

 botanical books, accordingly, in due order. 



(1) Dresser's " Eudiments of Botany." ' Sap ' not in the 

 index ; only Samara, and Sarcocarp, about neither of which 

 I feel the smallest curiosity. (2) Figuier's "Kistoire des 

 Plantes."* 'Seve,' not in index; only Serpolet, and She* 

 rardia arvensis, which also have no help in them for me. 

 * An excellent book, nevertheless. 



