82 BIRDS OF NORFOLK. 



tlie same remark applies to mucli larger pieces of water, 

 their long necks enabling tliem to perform an important 

 service to man by thus "cleansing the half stagnant 

 water courses," and consuming the submerged vegetable 

 refuse which would become offensive and obstructive at 

 the same time. They have their preferences, however, 

 in the matter of weed-diet, and on this head I cannot 

 do better than quote Mr. Dixon's experience for the 

 information of those who may desire to stock their 

 ponds or lakes with the most suitable vegetation. 

 Swans prefer, he says, ^' first what we call the lower 

 forms of vegetation, the confervce and the cheracice ; then 

 the Callitriche aquatica or water starwort, and the long 

 list of Potamogetons or pond- weeds. The rhizomata 

 of all sorts of reeds, rushes, arrow heads, &c., are 

 greedily torn up and devoured," but the roots of water- 

 lilies (white or yellow) " they scarcely ever touch except, 

 perhaps, in a young state," though they probably devour 

 the seeds. " The soft starchy parts of aquatic plants" 

 are selected when in a state of freedom, as in confine- 

 ment "the spare garden stuff, spinach, &c., thrown out 

 to them, is liked all the better for having laid soaking 

 at least twenty-four hours ;" and their preference for 

 food in a sodden state is sufficiently indicated by their 

 peculiar method of feeding, rinsing each mouthful in 

 water before swallowing it. Being an introduction only of 

 late years we find no mention in this bill of fare of that 

 greatest pest of our Broad waters and marsh drains, the 

 American Anacharis alsinastrum, or " Cambridge* weed" 

 as it is here commonly termed, but I have reason to 

 believe, from enquiries recently made, that swans are 

 of great service in keeping down, if not in extir- 

 pating, this transatlantic " difficulty." At Hoveton, 



* The history of its introduction into the waters of East 

 Anglia from that seat of learning, has a moral which should not 

 be lost on members of Acclimatization Societies. 



