Because their larva is almost a span long, and then much larger than the perfectly formed animal. The animal also retains its tail for some time after the four legs have acquired their perfect form and size.
Because it climbs trees in search of insects; for which purpose it has the extremities of the toes expanded, with suckers beneath.
The clammy slime with which it is covered, like serpents, serves also to support it among the leaves of the trees in which it lives.
Because the young of the common frog living in grass, among bushes, etc. come out in vast numbers, after warm summer showers. - Blumenbach.
Stories of showers of frogs have, however, obtained credence in our times. Mr. Loudon observes, when at Rouen, in September, 1829, " we were assured by an English family resident there, that during a very heavy thunder shower, accompanied by violent wind, and almost midnight darkness, an innumerable multitude of young frogs fell on and around the house. The roof, the window-sills, and the gravel walks were covered with them. They were very small, but perfectly formed, all dead ; and the next day being excessively hot, they were dried up to so many points or pills, about the size of the heads of pins. The most obvious way of accounting for this phenomenon is by supposing the water and frogs of some adjoining ponds to have been taken up by the wind in a sort of whirl or tornado." - Magazine of Nat. Hist.
Because it does not adhere to the subjacent parts, as in other animals, but is attached to them only at a few points, and is unconnected elsewhere.
According to old Walton, " the mouth of the frog may be opened from the middle of April till August, and then the frog's mouth grows up, and he continues so for at least six months without eating."
Because the animals have entered a deep crevice of the rock, and becoming torpid, have been covered with sand, which has afterwards concreted around them. Thus removed from the influence of the heat of spring1 or summer, and in a place where the temperature continued below the point at which they revive, it is impossible to fix limits to the period during which they may remain in this torpid state.
Such is the explanation of this phenomenon, by Dr. Fleming. An ingenious French naturalist, M. Geoffrey St. Hilaire, thinks it gives a very inaccurate idea of the phenomenon, " to assimilate the state of those beings whose lives are preserved in torpidity to the animals benumbed during winter." According to his theory, we must conclude that " there exists, for organization under certain combinations, a state of neutrality intermediate between that of life and death, a state into which certain animals are plunged in consequence of the stoppage of respiration, when it would take place under determinate circumstances."