254 PROCESS OF DEVELOPEMENT. GHAP. IV. 



seating no concentric or divergent layers, and no 

 medullary canal but merely an assemblage of large 

 and woody fibres, interspersed without order in a 

 pulp or parenchyma, softer at the centre and 

 gradually becoming harder as it approaches the cir- 

 cumference ; which structure they possess indeed in 

 common with many animals. But the grand and 

 peculiar feature by which they are distinguished 

 from all other plants is that of the origin and mode 

 of the annual augmentation of their stem. 



When the seed of the Palm-tree germinates it 

 protrudes a circular row of leaves, or of fronds, 

 which crowns the radicle, and is succeeded in the 

 following year by a similar row issuing from the 

 centre or bosom of the former leaves, which ulti- 

 mately die down to the base. This process is con- 

 tinued for four or five years successively without 

 exhibiting as yet any appearance of a stem, the 

 remaining bases of the leaves or frond forming by 

 their union merely a sort of knob or bulb. At last, 

 however, they constitute by their union an incipient 

 stem, as thick the first year as it ever is after; 

 which in the following year is augmented in height 

 as before, and so on in succession as long as the 

 plant lives, the leaves always issuing from the sum- 

 mit and crowning the stem which is a regular 

 column, but decaying at the end of the year, and 

 leaving circular marks at their points of insertion, 

 which furrow the surface of the plant, and indicate 

 the years of its growth. 





I 



