ture reached 58° F. the bodies of the young retained their warmth, and that under such conditions even a night's exposure had little, if any, effect; so that even supposing that the parents were absent during the night, the death of the young cannot be said to have been due to a failure of the parental instinct, because under normal conditions—and under such has their instinctive routine been evolved—their absence would not have prejudiced the existence of the offspring. I attribute the collapse of the young solely to the exceptional cold that prevailed at just the most critical time, and I base this conclusion partly on the experience gained from experiment, but mainly on their condition observed at different intervals; for during exposure they collapsed rapidly, their flesh became cold and their movements sluggish, their response grew weak, and gradually they became more and more feeble until they could scarcely close their bills after the mandibles had been forced asunder. Yet, even after having reached so acute a stage of collapse, the warmth from the body of the brooding bird was sufficient to restore them temporarily; once more they would become lively and responsive, only, however, to revert to the previous condition soon after the parent had again abandoned them. Doubtless their power of resistance grew less and less during each successive period of exposure.
If the nestling Bunting is to be freed from the risk of exposure, it is evident that there
