FACULTIES OF TTIK MIND. 295 



wards. It would, however, be a hopeless task, to enume- 

 rate the endless variety of gesture employed by other qua- 

 drupeds and by birds, since each species uses gestures 

 which are peculiar to itself, and suited to the organs with 

 which it is furnished. The practical naturalist, indeed, 

 studies these with care, as constituting one of the most de- 

 lightful employments of his science. 



In using these gestures, animals, in general, employ 

 sounds at the same time. If a crow is alarmed, and wishes 

 to communicate its fears to the flock, it not only assumes 

 a particular flight, but utters a cry which renders its feel- 

 ings intelligible, not only to those of its own kind, but even 

 to other birds and to quadrupeds. It may often be observ- 

 ed that ducks in a pond, upon a particular motion of diving 

 being performed as a signal, and a cry uttered by one, be-> 

 gin to dive and swim about in the water as if urged by one 

 common impulse, and execute the most complicated and ra- 

 pid evolutions in all the apparent giddiness of joy. But the 

 motions of the flocks of Purrs (Tringa alpina), indicate a 

 still more perfect system of signals. When flying, they keep 

 their backs for a time all in one direction ; and as suddenly, 

 by a change of position, exhibit their bellies to the spectator. 

 The change of position is very obvious, as their dusky 

 backs, when directed to the observer, exhibit the flock as a 

 dark cloud, which is changed to white, by the exhibition of 

 the light-coloured feathers of the under side. Linnets, and 

 several congregating birds, act in a similar manner. 



I have said, that man comprehends the natural expres- 

 sions of the lower animals, and even hinted that they in 

 part understand the gestures of one another. The dog 

 and cat, however, are, perhaps, the only animals which can 

 discern in the face of their master, the expressions of ap- 

 probation or displeasure ; and, by their behaviour, testify 

 that they feel their influence. 



