WHITETHROAT 
ment was this, that the leaf was often removed and dropped 
some distance away from the nest, but not infrequently 
swallowed. Both male and female acted precisely in the 
same way. 
Here, then, by a happy chance, an incident occurs which 
seems to momentarily lift the veil so completely shrouding 
the subjective states of the lower animals. We can well 
understand how necessary it must be for the welfare of the 
offspring that the nest should be uncontaminated by the 
excrement, and in many cases Nature has provided means 
whereby this end can be attained. In those instances in 
which the nest is enclosed, or lightly and loosely built of dead 
vegetation, it is even more essential that the means should be 
in every way adequate; and we find, as a rule, that this is 
the case, for the feeces are enclosed in this membraneous sac, 
which the parents are thus enabled to remove in their entirety. 
But amongst other species, where the complete cleanliness of 
the nest is not of so great importance, the young are them- 
selves able to eject the feeces over the side of the nest. We 
therefore see at work a series of activities. which, combined, 
result in a perfect system of cleanliness; the parent bird 
brings food and delivers it into the gape of a young one, it 
then waits for the feeces to be ejected, and if this is not done 
administers a slight tap with its bill on the anus, which is 
sufficient to produce the desired result. It then carefully 
lifts the membraneous sac, and, flying away, drops it some 
distance from the nest. 
There can be little doubt that the whole procedure is 
congenital, for how, otherwise, should a young one know how 
to respond to the touch of the parent’s bill? or how could 
the parents know what, under the circumstances, was 
necessary? In neither case could it have been learnt by 
tradition. 
The system is perfect, and we can recognise the need of 
removal, but it isnot so easy to understand what useful purpose 
is served by the swallowing of the excrement; the removal 
1.8) 
