CLOVERS 189 
foot Trefoil, connected not with its flower, but with 
its roots. If you pull up a plant from the ground, you 
will find little galls, or tubercles, attached to the roots, 
and you would find the same in a large number of 
members of the family. Now, at first, people thought 
these were simply a symptom of disease, and this idea 
was thought to be strengthened when it was found that 
these tubercles simply swarmed with colonies of some 
kind of those small funguses which you were told of 
in Chapter VII., and which are called “ Bacteria.” But 
more careful examination tends to show that these are 
among the useful bacteria, “paying guests” in fact, and 
that it is a case of partnership, such as we saw among the 
lichens. It has been known for some time that many 
of the clover tribe got more nitrogenous compounds from 
the soil than seemed possible, and it has been suggested, 
with great possibility of truth, that these bacteria can 
do what the bigger plant cannot, and that is, take up 
the nitrogen of the air and work it up into suitable 
food material! It cannot be said that this is proved 
as yet, but it is probable, and suggests still wider possi- 
bilities of co-operation in nature. 
The Stonecrops, to which belong almost all our English 
plants with fleshy leaves, we must pass by, only remark- 
ing that the flowers of most of them recall small, starry 
potentillas, which, with the leaf-structure, identifies them 
at once. The Wall-Pennywort has leaves stalked like the 
White-rot and spikes of greenish-yellow flowers, and is’ 
common enough in the West of England. The Saxifrages 
must also be left on one side, with the reminder that 
the London Pride of our gardens has fairly typical 
flowers, or, better still, the beautiful Meadow Saxifrage, 
with its pure white flowers and bulbous tubers at the 
roots, like small potatoes. 
