Chap. XIV.] INSTINCT: ITS NATURE AND ORIGIN. 221 



Actions which take place independently of Will as an 

 instigator and with machine-like regularity, are, as the 

 reader is now aware, known to physiologists as * reflex ' or 

 * automatic' actions. All the acts above mentioned belong 

 to this category, and these particular examples are further 

 characterized by the fact that the impressions which incite 

 them are altogether unfelt. They are results, that is, of 

 unconscious impressions. Many other automatic actions, 

 however, exist — sneezing and coughing being examples — 

 in which this latter peculiarity is wanting. 



But why, it may be asked, are the actions above speci- 

 fied performed with such undeviating regularity, and at 

 the instigation of mere unconscious impressions ? 



During the untold ages, in which organisms have existed 

 with food-taking propensities and alimentary canals, con- 

 tractions of the Intestine have been ensuing at short 

 intervals, in response to the stimulus supplied by food. 

 Since contractile Hearts were first evolved, they have never 

 ceased to beat in the lineal descendants of inconceivably 

 numerous generations of slowly modifying animal types. 

 The contractions of Oviducts or of the Womb, as well as 

 the movements concerned in Eespiration, also had their 

 beginnings in forms of life whose advent is now buried in 

 the immeasurable past. 



Let us, however, place side by side with these consider- 

 ations, the well-known fact that one of the essential 

 peculiarities of nervous action is, that movements which 

 are at first executed slowly and irregularly, may, after 

 numerous repetitions, become rapid and regular — more 

 especially if on successive occasions the stimuli are similar, 

 and nothing intervenes to alter the manner in which 

 the recurring acts are performed. It need not, therefore, 

 surprise us — especially after what w^e have learned as to 

 the genesis of ' reflex ' actions — to find that the contrac- 



