48 THE PRINCIPLE OF Chap. I. 



I will give only one other instance of an habitual 

 and purposeless movement. The Sheldrake (Tadorna) 

 feeds on the sands left uncovered by the tide, and when 

 a worm-cast is discovered, " it begins patting the ground 

 with its feet, dancing as it were, over the hole; " and this 

 makes the worm come to the surface. Now Mr. St. John 

 says, that when his tame Sheldrakes " came to ask for 

 food, they patted the ground in an impatient and rapid 

 manner." 19 This therefore may almost be considered 

 as their expression of hunger. Mr. Bartlett informs 

 me that the Flamingo and the Kagu (Bhinochehis 

 jubatus) when anxious to be fed, beat the ground with 

 their feet in the same odd manner. So again King- 

 fishers, when they catch a fish, always beat it until it is 

 killed; and in the Zoological Gardens they always beat 

 the raw meat, with which they are sometimes fed, before 

 devouring it. 



We have now, I think, sufficiently shown the truth 

 of our first Principle, namely, that when any sensation, 

 desire, dislike, &c, has led during a long series of gen- 

 erations to some voluntary movement, then a tendency 

 to the performance of a similar movement will almost 

 certainly be excited, whenever the same, or any anal- 

 ogous or associated sensation &c, although very weak, 

 is experienced; notwithstanding that the movement in 

 this case may not be of the least use. Such habitual 

 movements are often, or generally inherited; and they 

 then differ but little from reflex actions. When we treat 

 of the special expressions of man, the latter part of our 

 first Principle, as given at the commencement of this 

 chapter, will be seen to hold good; namely, that when 

 movements, associated through habit with certain states 



19 



See the account given by this excellent observer in 

 ' Wild Sports of the Highlands,' 1846, p. 142. 



