VH On the Habits and Food of the Stickleback. [March, 



choice. These were found to be preferred to all other ahtnent, 

 and for a month at least they had scarcely any other food. The 

 species of leeches procured were the Hirudo sanguisuga, the 

 H. vulgaris, and the H.compJanata. To ascertain what size of 

 leech would be swallowed, a male stickleback, of about an inch 

 and three-quarters in length, was selected, and put in a large 

 tumbler on a mantel-piece, where its mode of attacking and 

 devouring its prey formed a source of amusement to the children 

 for weeks. 



On putting the leeches into the water, the stickleback darted 

 round the tumbler with lively motions, till it found a leech 

 detached, and in a proper situation for being seized. When the 

 leech was very small, say about half an inch in length, it was 

 often swallowed at once before it reached the bottom of the 

 vessel ; but when a larger one, about an inch, or an inch and a 

 half in length, in its expanded state, was put in, and had fastened 

 itself by its mouth to the glass, the efforts of the stickleback to 

 seize and tear it from its hold were incessant, and never failed to 

 succeed. It darted at the loose extremity, or when both ends 

 were fastened at the curve in its middle, seized it in its mouth, 

 rose to near the surface, and after a hearty shake (such as a dog 

 would give a rat) let it drop. The leech, who evidently wished 

 to avoid its enemy, upon its release again attached itself by its 

 mouth to the glass ; but again and again the attack was 

 repeated till the poor leech became exhausted, and ceased to 

 attempt holding itself by its disc. The stickleback then seized 

 it by the head in a proper position for swallowing, and after a 

 few gulps the leech disappeared. The H. complanata, being of 

 an ovate form, and having a hard skin, was not attacked, unless 

 when very young, and scarcely two or three lines in length ;* 

 and leeches of the other species, when pretty well grown, or 

 longer than himself when expanded, were killed in the manner 

 above-mentioned, but not swallowed. In one of his attempts to 

 seize a leech, the stickleback having got it by the tail, the 

 animal curled back, and fixed its disc upon its snout. The 

 efforts of the stickleback to rid himself of this incumbrance 

 were amusing. He let go his hold of the leech, which then 



* It may be mentioned as a curious instance of the wonderful arrangements of nature 

 in securing the continuance of species, that the young of the H. complanata, which I have 

 generally found attached to aquatic plants, were, in one instance which fell under my 

 notice, affixed to the under surface of the parent leech. This animal which, unlike most 

 of its congeners, never swims, had fastened itself to the side of the glass, and three young 

 ones, about a line in diameter, were thus exhibited to view in a most interesting light for 

 an animal so low in the scale of existence. Thus protected, there was nothing to fear 

 from the attacks of the stickleback, or other enemies. They moved occasionally on the 

 disc of the mother, and it is conjectured might remain in that situation, imtil they had 

 attained such a size as to render further care on the part of the parent unnecessary. To 

 convince myself that this protection was requisite, I detached one with the point of a 

 knife, which was instantly devoured by the stickleback. The young H, complanata^ 

 from its transparency, forms a beautiful object for the microscope. 



