On the Growth of Birds.—The author's observations on this subject are chiefly confined to the martin, the common fowl, the turkey, and goose. They all tend to show a rapid growth, varying in degree according to the habits of the species. The young martin was found on leaving its nest heavier than the parent bird; and this the growth, as to time, of about twenty days, reckoning from the hatching of the egg. A turkey poult, the day it quitted the egg, weighed one ounce and three quarters; in five months it had increased to ten pounds. A gosling, in thirty-four days, had increased in weight from six ounces to six pounds.