24 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
would indeed be more profitable to deal at this stage with 
such subjects as emulsions and the permeabilities of porous 
membranes and to consider how far they support, or are 
reconcilable with, the unorthodox views advocated con- 
cerning the existence of expansile surface strata. 
Until the simpler surface phenomena are reasonably 
intelligible little real progress will be made with the more 
complex, and I shall hope that this address will enable the 
student to acquire something approaching to a real grip of 
the fundamentals of the subject. 
