THE PHYSIOLOGY OF SOWING SEEDS. 623 
growth. Not only does this destroy all the 
weeds which may have vegetated with the grain, 
or with the plants cultivated, but it increases the 
growth considerably, by multiplying the extent 
of the fibrils of the root. For it is a fact which 
cannot be too well remembered, that the more 
you cut off the fibrils of the roots, by stirring 
and aerating more the soil around them, the 
more you increase their tendency to multiply. 
This advantage is especially seen, in harrowing 
crops of wheat in the spring, after the frosts of 
winter are ended, and growth has begun. In 
drill husbandry, however, are the vast advantages 
of such a course best seen. ‘There you can hoe 
among your plants, and loosen the surface soil 
between the drills, without injuring the plants, 
and the increased vigour after such hoeings is very 
soon manifest. But it is among the potatoe and 
and turnip crops where the stirring of the soil 
is the most marked in its results. There you 
can use drill harrows to run between the drills 
to destroy all the weeds and loosen the soil; 
there you can plough between the drills, once or 
twice, before the plants are sufficiently grown to 
be injured by the process. And the result of 
this is not merely to destroy all the weeds, as 
was the intention by having recourse to this 
