INTRODUCTION 5 
slip, as in the case of the banks of railway cuttings. 
The most troublesome case is that of slip, of which the 
cause is easy to formulate. When the banks dry in 
summer the surface cracks; and later on, by these 
cracks, water gets access, rendering a deep-seated zone 
plastic so that the superficial layer tends to slide down 
the incline. As a consequence, railway companies are 
put to great expense in remedial measures, especially 
drainage, cutting away material so as to reduce the angle 
of slope, constructing brickwork and masonry, etc. 
Probably this particular sort of trouble could be 
met by appropriate afforestation, and it is remarkable 
that the companies should not possess in common an 
experimental department of forestry to advise them 
on these and analogous problems. Perhaps something 
of the kind may be established in the future should our 
railways remain permanently under unified control 
after the war. 
Tue BoTANICAL EXPLORATION OF THE EMPIRE 
A matter of the first importance, if our vast resources 
are to be properly and systematically utilised, is the 
botanical exploration of the empire. 
In his interesting Address as President of the 
Botanical Section of the British Association at New- 
castle-on-Tyne, Dr. A. B. Rendle alluded to the way 
in which in the past our possessions have been explored, 
and expressed the hope that it might be possible to 
arrange an Imperial Botanical Conference after the war, 
at which matters of this kind could be discussed. This 
