404 THE UNIVERSE. 



CHAPTER Y. 



GROWTH. 



THE growth of our trees was for long an impenetrable 

 mystery. 



Duhamel maintained that it was the bark which produced 

 the wood, and for more than a century this was believed on 

 the faith of the celebrated academician, who had made so 

 many experiments on the subject. It did not occur to any 

 one to ask him from whence the bark came. 



After many discussions it has at last been shown that the 

 woody structure and its envelope grow at their, junction, 

 each in its own way : the bark growing towards the inte- 

 rior, the wood outwards by concentric layers, which are 

 piled up one above the other. One is produced each year, 

 so that by counting the circular zones at the base of a 

 trunk their number gives the exact age of a tree. 



Long before this fact had been taught as a dogma by 

 botanists it was known to the vulgar. Mention is made of 

 it in Michel Montaigne's " Voyage en Italie," a singular 

 production, wherein, instead of Italy, we find only a list and 

 the effects of different remedies which the illustrious Mayor 

 of Bordeaux employed in every town he passed through. 

 A journeyman turner showed him that he could compute 

 the age of trees very well from sections of them. " He 

 taught meV' he says, " that all trees bear as many circles 

 as they have endured years, and pointed it out to me in all 

 those he had in his shop. And that part which looks to- 



