50 HISTORY OF BRITISH ZOOPHYTES. 



ment for the insect race. Plants are covered with aphides, 

 greedily sucking their juices, and constantly, as it would 

 seem, in the act of sucking. It cannot be doubted but 

 that this is a state of gratification. What else should fix 

 them so close to the operation, and so long ? Other species 

 are running about, with an alacrity in their motions which 

 carries with it every mark of pleasure. Large patches of 

 ground are sometimes half-covered with these brisk and 

 sprightly natures. If we look to what the waters produce, 

 shoals of the fry of fish frequent the margins of rivers, of 

 lakes, and of the sea itself. These are so happy that they 

 know not what to do with themselves. Their attitudes, 

 their vivacity, their leaps out of the water, their frolics in it 

 (which I have noticed a thousand times with equal attention 

 and amusement), all conduce to show their excess of spirits, 

 and are simply the effects of that excess. Walking by the 

 sea-side in a calm evening, upon a sandy shore, and with 

 an ebbing tide, I have frequently remarked the appearance 

 of a dark cloud, or rather very thick mist, hanging over the 

 edge of the water, to the height perhaps of half a yard, and 

 of the breadth of two or three yards, stretching along the 

 coast as far as the eye can reach, and always retiring with 

 the water. When this cloud came to be examined, it proved 



