LECTURE IE 
48. But it is time to turn from general considerations 
to some of the details upon which they are founded. 
49. If the nature of vegetation is rightly considered, 
a symmetrical arrangement is almost inevitable; for 
what is a plant in the beginning ? If we take it at 
the earliest period in which its existence can be dis¬ 
covered, it is found to be a point, whatever magnitude 
it may ultimately acquire; that point gradually 
becomes a sphere, so that it would not be inaccurate 
to represent the birth of vegetation by a circle. Up 
to a certain time there is a force acting from the 
centre to the circumference of this sphere; but after 
a time the sphere acquires polarity — that is to say, 
its poles lengthen, and thus we have either a cylinder 
or a double cone. 
50. Such is an abstract notion of a plant. As soon 
as this extension upwards and downwards occurs, the 
tendency to assume a spherical form disappears, or 
becomes so disguised that it is difficult to recognise. 
The force of development then expends itself in a 
somewhat centrifugal manner, operating in planes at 
a short distance from the axis of the stem or main 
body whence it proceeds. 
51. Eventually the results of this manner of growth 
become visible in a successive formation of parts. 
