The First Land Plants 
crop through inoculation, the evidence seems on the 
whole distinctly against nitrobacterine. Every attempt 
seems to have been made to make the trial as complete 
and as fair as it could possibly be.° 
But though all these three cultures (nitragin, nitro- 
culture, and nitrobacterine) are found to-day not to 
answer when tried commercially by ordinary gardeners 
and farmers, the ideal of a tamed bacterial population 
which one can cherish in test-tubes and sow carefully in - 
spring-time with a distinct prospect of an abundant 
harvest will assuredly be obtained if only people will not 
be discouraged by these repeated failures.* 
But nitrates form but one of the many salts which 
must somehow be gathered in by the roots which have 
to provide a constant stream of water for all the grow- 
ing or active cells. 
The layer of soil upon which plant life depends is ex- 
ceedingly thin. It is hardly ever more than a few feet, 
and often is but a very few inches in thickness, But 
one requires a touch of imagination, of sympathy with 
bacteria and with earthworms, if one is to at all appre- 
ciate the wonderful character of the processes at work. 
The earth itself is porous and crumbly, made up of 
tiny sharp-edged particles utterly irregular in shape, 
varying in size, and of the most different constitution. 
Some are organic, others inorganic; there may be 
particles of sharp quartz which have defied plant action 
from the beginning of the world, and beside them silt 
or sand fragments which have been devoured by worms, 
rolled by water, attacked by acids, and utterly trans- 
formed in every geological period from the Silurian: to 
our own days. One has first to realise the labyrinth of 
* Full details of the tubercle bacteria will be found in Chittenden, Zc. ; also 
Bull. U.S.A. Agriculture Plant Industry, 71, 1905, and especially Jacobitz, 
C. B. f. Bact., Jena, 1901 Nos. 22-24. 
48 
