All of the phenomena occurring in living matter, the 

 phenomena which it is the avowed purpose of physiology to 

 study, are ultimately referable to changes occurring in 

 the living cells of which it is composed. Many of the phen- 

 omena occurring in living matter, such as secretion, move- 

 ment, irritability, and growth, can readily be referred to 

 the more fundamental changes in the living cells; but the 

 attempt to interpret rmy single property of a living cell, 

 such as growth, division, contraction, in terms of physics 

 and chemistry, or in any other way, has thus far led to no 

 result satisfactory to the minds of scientific inquirers. 

 Nevertheless, it seems that this is the task which lies 

 before the science of physiology on its way toward becoming 

 an exact science: the task of interoreting and explaining 

 the fundamental properties of living cells. 



One who turns his attention to the direct study of the 

 living cell may be at a loss how to begin. It is undoubted- 

 ly ov/ing to the technical difficulties of the subject that 

 it has not already been further advanced. We are dealing 

 with tiny objects of an almost inconceivably delicate con- 

 stitution, morphologically very complex, and chemically of 

 far greater complexity than any other knovm substance; and 

 to these mysterious little objects are to be attributed 

 all of the. various phenomena of living matter; for all of 

 the activities of living matter may be ultimately referred 



(4) 



