220) LIFE OF A TREE. 
nor seed formed during the first year; but all 
this takes place in the second year,—after which 
the plant perishes. Then come Perennials, which 
complete their round of developement in the year, 
die down in Winter, and rise again with new glory 
and vigour in the following Spring. “In most 
woody plants,” says M. Mirbel, ‘‘ death does not 
occur until fructification has recurred for a 
greater or less number of years; some of the 
monocotyledonous (Endogenous) plants however, 
such as the Sago-tree and Umbrella-tree, with 
immense fan-formed leaves of eight or ten yards 
in length, only bear fruit once, and then die.” 
*‘In proportion,” continues the same author, 
‘‘as a tree increases in size, the vessels of its 
woody layers become obstructed, and the sap 
circulates with less freedom. Hence, absorption 
and secretion decrease after youth, in proportion 
as the bulk of the tree is enlarged; the bark 
becomes less vigorous; the buds and roots be- 
come fewer and feebler; the branches wither; 
the stem decays at the head; water settles in the 
injured parts ; and the wood moulders away.” 
There are a number of causes which may 
hasten the death of plants, irrespective of the 
