WORK OF BACTERIA 
53 
and supplies him with artificially grown bacteria with 
which he may inoculate the soil or seed. If the soil 
is favorable otherwise, the crop is greatly increased 
and in time the soil made more profitable for other 
crops. 
The wise farmer does not plant potatoes or corn 
in the same piece of ground two years in succession, 
unless he adds large quantities of fertilizer or plant 
food. He rotates his crops because different species 
of plants take from the soil different kinds or amounts 
of food. 
Even if these two fields of work—scavenging and 
aid in agriculture—were all in which we make use of 
bacteria, their claim of helpfulness would be over¬ 
whelmingly proved; but other results of decomposition 
processes are valuable in the arts and in the commerce 
of the world. 
By the action of bacteria upon the whitish juice of 
certain plants fermentation processes are set up which 
result in the blue indigo so important in dyeing indus¬ 
tries. Our grandmothers would have been surprised 
indeed had they understood that their solid bluing was 
once a white liquid. 
Bacteria, too, make possible the retting of the flax, 
whereby the fibres are separated from the stalk to be 
finally woven into the beautiful “pictures in white” 
we call table damask. 
They bear their part in the preparation of sponges 
and in many processes of tanning and tobacco curing. 
Rotation 
of Crops 
Fermentation 
Processes 
