ZOOLOGY. 359 



ness and weight; he began then to weigh both the bird and its food, and 

 the results were given in a tabular form. On the fifteenth day he tried a small 

 quantity of raw meat, and, finding it readily eaten, increased it gradually to 

 the exclusion of worms; with it the bird ate a large quantity of earth and 

 gravel, and drank freely after eating. By experiment it appears that though 

 the food was increased to forty worms, weighing twenty dwt., on the eleventh 

 day, the weight rather fell off; and it was not until the fourteenth day, when 

 he ate sixty-eight worms, or thirty-four dwt., that he began to increase 

 on this day the weight of the bird was twenty-four dwt. ; he therefore eat 

 forty-one per cent, more than his own weight in twelve hours, weighing 

 after it twenty-nine dwt., or fifteen per cent, less than the food he had eaten 

 in that time; the length of these worms, if laid end to end, would be about 

 fourteen feet, or ten times the length of the intestines. To meet the objec- 

 tion that the earth-worm contains but a small amount of solid nutritious 

 matter, on the twenty-seventh day he was fed exclusively on clear beef, in 

 quantity twenty-three dwt.; at night the bird weighed fifty-two dwt., but 

 little more than twice the amount of flesh consumed during the day, not 

 taking into account the water and earth swallowed. This presents a won- 

 derful contrast with the amount of food required by the cold-blooded verte- 

 brates, fishes and reptiles, many of which can live for months without food ; 

 and also with that required by mammalia a man, at this rate, should eat 

 about seventy pounds of flesh a day, and drink five or six gallons of water. 

 The question immediately presents itself, how can this immense amount of 

 food, required by the young birds, be supplied by the parents? Suppose a 

 pair of old robins with the usual number of four young ones these would 

 require, according to the consumption of this bird, two hundred and fifty 

 worms, or their equivalent in insects or other food daily suppose the par- 

 ents to work ten hours, or six hundred minutes, to procure this supply ; this 

 would be a worm in every two and four-tenths minutes; or each parent 

 must procure a worm or its equivalent in less than five minutes during ten 

 hours, in addition to the food required for its own support. He was unable 

 to reconcile this calculation with actual observation of robins, which he had 

 never seen return to their nests oftener than once in ten minutes. After the 

 thirty-second day the bird had attained its full size, and was entrusted to 

 the care of another person during his own absence of eighteen days ; at the 

 end of that period the bird was strong and healthy, with no increase of 

 weight, though its feathers had grown longer and smoother. Its food had 

 been weighed daily, and averaged fifteen dwt. of meat, two or three earth- 

 worms, and a small quantity of bread each 'day; the whole being equal to 

 eighteen dwt. of beef, or thirty-six dwt. of earth-worms ; and it has contin- 

 ued to eat this amount to the present time. The bird having continued, in 

 its confinement, with certainly .much less exercise than in the wild state, to 

 eat one-third of its weight of clear flesh daily, he concludes that the food it 

 consumed when young was not much more than must always be provided 

 by the parents of wild birds. The food was never passed undigested; the 

 excretions were made up of gravel and dirt, and a small quantity of white 

 semi-solid urine. 



He thought that every admirer of trees may derive from these facts a 

 lesson, showing the immense power of birds to destroy the insects by which 

 our trees, especially our apples, elms, and lindens, are every few years 

 stripped of their foliage, and often many of them killed. The food of the 

 robin, while with us, consists principally of earth-worms, various insects, 



