THE ORIGIN OF NERVES. 279 



cule literally eats and digests without possessing a digestive 

 apparatus ; and, as we may note, " feels," in the absence 

 of the faintest traces of a nervous system. Watch a par- 

 ticle of food approach the amoeba, for instance, and you 

 may observe that when the article impinges against the soft 

 body of the animal, the protoplasm will be extended so 

 as to engulf the morsel, and the amoeba may thus be seen 

 to receive food simply by surrounding the food particles with 

 its soft elastic frame. Thus we may learn from a simple 

 observation that the protoplasm of which the amoeba's body 

 is composed is pre-eminently a contractile substance, and 

 that it is moreover highly sensitive. In these two conditions 

 the art of feeling may be said to begin. The sensitiveness 

 of the body is the primary condition ; and the power of 

 acting upon the impressions received by the sensitive medium 

 is the second essential in the process. Here also, in reality, 

 we have the beginnings of truly nervous acts. For there 

 can be no doubt that the animalcule " feels " the contact of 

 the food-particle, and that the result of the impression made 

 upon its body is to produce contraction depending on 

 molecular movement of the protoplasm, and to stimulate this 

 contractile protoplasm to engulf the morsel. The action 

 of the amoeba thus appears essentially of the nature of " re- 

 flex action " after all, and claims kindred with the simpler 

 acts of higher existence. 



If, now, we investigate the conditions of life in lower 

 plant organisms, we shall find the great difference between 

 most of these forms of life and their lower animal-neighbours 

 to consist in the development of a definite wall or envelope 

 to their bodies, or rather to the " cells " or minute structures 

 of which the lower plants are composed. That the proto- 

 plasm of which the lower plants are composed is essentially 

 similar in its physical characters to that seen in the lower 

 animals, is a chemically demonstrable fact. And when we 

 look through the microscope at the cells of a low plant, such 

 as Chara, we note the protoplasm or living matter of the 

 cells to be in a state of constant movement. Any one who 



