PREFACE TO THE FIRST EDITION ix 
prevalent that plants live upon inorganic materials ab- 
sorbed from the air and from the soil. This seems to 
indicate a fundamental difference between the modes of 
nutrition of animal and vegetable protoplasm. I have 
endeavoured to show that this view is erroneous and that 
both are nourished similarly. 
I have also tried to show that the sensitiveness of the 
plant and the animal is alike in properties, though differ- 
ences are apparent in the direction of its differentiation. 
I have avoided as far as possible the discussion of con- 
troverted points, feeling that this would be out of place in 
a work intended to serve as an introduction to the subject. 
Such matters are more properly treated of in the more 
comprehensive works to which I have already alluded. 
J. ReEyNoups GREEN. 
CamMBRIDGE, June 1900. 
b2 
