THE STEM OF VASCULAR PLANTS. 151 



that, with greater reason, we cannot agree with regard 

 to the use of it. The older naturaUsts, and some modern 

 ones, who believe in the sensibiKty of plants, regarded 

 it as being analogous to the brain ; but can this be a 

 brain which is obliterated each year, and is absent in so 

 many plants? Others, as the similitude of the names 

 indicates, have compared it with the marrow of the 

 bones of animals ; but the marrow is permanent and 

 continues fresh, and the pith becomes obliterated. Hales 

 and Mustel compare it with the substance which fills the 

 young feathers of birds, which dries up when they have 

 increased in size, and becomes, like the pith, a receptacle 

 of air. Others have compared it with the heart, lungs, 

 stomach, &c. ; but let us quit these useless comparisons, 

 and endeavour to study this organ considered by itself. 



Cesalpinus and Limiaeus thought that the pith gives 

 origin to the pistil ; they have been induced to form this 

 opinion from the similarity of situation which the pistil 

 and pith occupy in the flower and the wood. But all 

 Endogenous plants, in which there is no central pith, have 

 also a pistil, which is likewise in the centre of the flower. 



Magnol believed that the pith is destined to elaborate 

 the more perfect juices, not those which are necessary 

 for the simple nourishment of the wood, but such as are 

 made for the fruit ; and he tries to prove his opinion by 

 mentioning some trees with an abundant pith which bear 

 much fruit. But the branches which are not destined to 

 bear fruit, are not provided with less pith than the fruit 

 branches; several Exogens might be mentioned which 

 bear much fruit, and have very little pith ; and, lastly, in 

 most trees, the pith dries up before the time of flowering. 



It was, doubtless, an idea analogous to that of Mag- 

 nol which has led crardeners to sav that in order to 

 obtain stoneless fruits it is sufficient to destroy the pith 

 of the trees. Duhamel, who performed this experiment. 



