CHAPTER VII. 

 THE RESPONSIVE LIFE OF ORGANISMS. 



It is a long vista the science of biology opens to our 

 imagination. At the farther end is formless protoplasm, 

 moving with the first thrill of responsive adaptiveness tc 

 the external world. Along the way are ranged all the 

 form-changes and all the acquired powers of organic life. 

 At this end is the wonderful assemblage of living forms; 

 among them, the humai organism, with a mind that con- 

 templates all, and endeavors to understand all, and withal, 

 itself. 



Mind in man is made known in speech 

 and action; the psychic life of animals, 

 in actions alone. If the acts of animals 

 are like those we perform under similar 

 circumstances, we are inclined to infer 

 that animals possess kindred psychic 

 states. Thus, from their behavior, we 

 think we recognize hunger and satiety, 

 anger and fear, pain and pleasure, in 

 the expressions of animals, and, in- 

 FIG. 255. Melancholy, deed, some of the less instinctive feel- 

 ings, such as curiosity in monkeys and 

 jealousy in dogs. The great difficulty in interpreting 

 psychic states in beings other than ourselves lies, of course, 

 in the fact that the mind is directly accessible only to its 

 possessor. One may not know the mind of another being 

 except by inference. Great difficulties attend the inter- 

 pretation of the psychic states of even those animals that 

 are most like us in bodily organization, and the difficulties 

 become insuperable in the case of animals that lack our 



