594- THE POPULAR SCIENCE MONTHLY. 



are never performed without thought, although we may be able to 

 group them into classes, and to guide our conduct by general rules or 

 principles, either established by experience or accepted upon the 

 authority of others. The resemblance between these actions and 

 the instinctive ones is recognized in common speech, for we often hear 

 it said of a person who is guided in the main, in this way, by general 

 rules, and is often unable to assign any reason for a particular course 

 of conduct, that he or she is a person of fine natural instincts. 



The actions of the sailor, who guides his movements by the weath- 

 er reports from the Government Signal-Office, without understanding 

 or caring much about the way in which the reports are made out, are 

 still more rational, and further removed from instinct, although they 

 evidently fall into the series, and have much in common Avith those 

 actions last mentioned. Finally, the actions of " Old Probabilities " 

 himself belong to a still higher class, and are eminently rational. 



Reviewing the ground which we have passed over, we find that 

 living things present us with a series of more or less related ac- 

 tions. 



First, we have the mechanical and reflex actions of plants and 

 animals ; then the instinctive action, then the hereditary habit, then 

 the acquired habit ; next the action governed by a general rule, 

 established by experience; and finally the rational action. 



Great as seems to be the difierence between the two extremes of 

 this series when considered by themselves, it is possible to pass from 

 one to the other through a series of intermediate actions, without the 

 necessity for any great jump in any part of the series ; and it is plain 

 that, great as are the differences between them, they all have some- 

 thing in common. Let us try to discover what this something is. 

 All the actions which we have been examining are alike in this, that 

 they are directed to the accomplishment of a purpose. The root 

 grows downward in order that it may reach water. The leaf turns 

 with the sun in order that it may receive a greater supply of heat. 

 The fly-trap closes upon its prey and pours forth its secretion in 

 order that it may be supplied with food. The vine twines in order 

 that its long, slender stem may be supported. The digestive organs 

 perform their various functions that the body may be nourished and 

 its waste supplied. The eyelids close in order that the eye may be 

 shielded from danger. 



The chick instinctively seeks its mother that it may be protected 

 and fed ; and it hides from the hawk to save its life. The dog begs 

 and the soldier goes through his manual to escape punishment, or to 

 gain a reward or approbation, or perhaps from a combination of all 

 these motives with still higher ones, but in any case to accomplish a 

 purpose. The sailor watches the weather-predictions and regulates 

 his actions accordingly, in order that his voyage may be finished as 

 safely and quickly as possible. And the signal-officer publishes his 



