CHAPTER V. 
DEVELOPMENT. 
NV ez eo, ROM the embryo plant to the per- 
; Ne Me a 
% fected Tree, the ‘successive stages 
Se Le 
a 
of growth are accomplished in 
varying degrees of rapidity. The 
causes which promote a more 
rapid rate of growth in some 
species of plants than in others are 
amongst the mysterious facts relating 
x to the development of vegetable life. We 
can, more easily, ascertain the reasons for the dif- 
ference in the rate of progress in different indi- 
viduals of the same species; for they mostly arise 
from differing degrees of vigour, or from more or 
less favourable conditions of growth. But if we 
subject two young Trees of different species, each 
E 
