FERTILIZATION. 119 



bles, ihc constant lengtlicnin*^ of the roots, makin*!; llie cir- 

 culation loo extensive, are all causes constantly opcratintr to 

 prevent the duration of llie most of forest trees beyond one 

 or two centuries. But there are cases in which favorable 

 circumstances hove conspired to len«rthen out the lives of 

 particular imlividiials to as many thousands. Some trees 

 of ijreat ai;e have become subjicts of history. The cele- 

 brated Chestnut of Mount Etna has a circumference of IGO 

 feet, and is called caslai^no di cento cavalli^ the Chestnut of a 

 hundred cavaliers, as it is said that when the Queen of Arra- 

 gon was on her way to Naples she desired to visit Etna, and as- 

 cended the mountain with a hundred cavaliers — a storm com- 

 ing upon them, ihey were all sheltered by the foliage of this 

 collossal tree. This tree has been said to be several trees 

 united, but more recent and accurate observations have pro- 

 ved it to have but a single root, and of course it is a single 

 tree. Its age by any calculation must be that of many cen- 

 turies. Some of the oldest Cedars of Lebanon are suppo- 

 sed to have an age of two thousand years. The Baobab 

 trees of Africa, and the Dragon tree of Orotava are said to 

 be even six thousand years old. Pliny believes there were 

 trees in his time as old as the world, as he says they were, 

 *' iniacta (Ptns et congenita wundo, untouched by age and 

 brought forth nith the world." 



Means have been devised for the determining the ages of 

 trees by the diarnete.'s, but they are so liable to error, that 

 that they are unworthy of repetition. 



CHAPTER V. 

 Section 1. Fertilization. 



149. The subject of fertilization is one of much interest, 

 from the singularity of the operations by which it is in some 

 cases carried on, and the beautiful adaptation of the means 

 to bring about this indispensable end. 



All plants possess some apparatus for the production of 

 seed, or of bodies which, independent of the parent will vege- 

 tate and produce the species. Prom the most simple Con- 

 fervie, with stems scarcely larger than films of silk, to the 

 most perfect plants. The fact that some plants possessed 

 two systems by whose conjoined action the fruit and seed 

 were perfecied, has been long known. The ancients were 



