THE PHYSIOLOGY OF SOWING SEEDS. 619 
the soil; so that ere long, there is a tuft of 
blades and culms upward in the air, with a cor- 
responding tuft of roots downward into the soil. 
A period, however, soon arrives when this in- 
crease in the number of culms and of roots 
ceases; stooling, or “branching,” is over, and 
the plant rises rapidly into blade and _ straw, 
preparatory to the last stage of its growth, 
fructification and maturation. The healthy and 
vigorous condition of this growth, is alway indi- 
cated by a full and deep green in the blades; 
where this is not the case, either there are too 
many plants on the ground, or the soil lacks a 
sufficiency of azotised matter, to enable the plants 
to thrive as fully as they ought. This vigour 
of growth continues until the plants shoot out 
into the ear, and then growth entirely ceases. 
A comparative examination of vigorous plants 
at this period when vegetation has attained its 
ultimate object, and built and reared the whole 
fabrick of the plant’s system, shows us one of the 
two following results. If the roots have but a 
moderate developement, and there be but a moder- 
ate quantity of loose soil in which they can 
extend themselves, then the vigour of the growth 
has arisen from the great quantity of nutritive 
