for the egg and for the helpless offspring; and, in the third place, it must be so situated that the young can reach the water in safety. We will examine these conditions one by one.
The proximity to the food-supply is a consideration of some importance. The life of the Guillemot during the winter is a strenuous one; we know that large numbers succumb in stormy weather, and we can infer that slight constitutional defects might make all the difference between failure and success; and, therefore, the less severely the constitution of the parent is taxed during reproduction, and the more securely the constitution of the offspring is built up, the greater prospect will both have of resisting the hardships of the winter successfully. Much, then, will depend upon the distance the parents have to travel in order to obtain food. The farther the breeding station is removed from the feeding ground the greater the physical strain which will be imposed upon the birds, and the greater the chance will there be of the offspring being improperly nourished. Now the food consists of small fish, largely of sand-eels, which are secured in deep water, and the abundance of which varies, possibly according to the nature of the currents. Hence cliffs which are situated away from the water, or from which the water recedes at low tide, or which are surrounded by an area of shallow water, and are thus not in proximity to the feeding ground, even though
