Page:The British Warblers A History with Problems of Their Lives - 9 of 9.djvu/37

 ought not to be carried out near the limit of the breeding range of a species, where from other causes unpaired individuals of both sexes may be of not uncommon occurrence. Are we not, however, attaching too great an importance to this imperfection in the first test? Is it not a question of average, and will not the struggle for territory over a long period of time be sufficient at least to maintain that standard of efficiency which is necessary to ensure the position of the species in the struggle for existence? I am inclined to think it will, while at the same time recognising the point as a debatable one.

That the male displays his charms before the female, and that she on her part appreciates the display and exercises a deliberate choice, was at one time deemed possible, but so many and so weighty were the objections which were raised that biologists searched about for a more reasonable interpretation. Such an one they found in the modification proposed by Professor Groos, who, fixing his attention upon the necessity for some effective means of hindering a too liberal yielding to the sexual impulse, saw in the reluctance of the female a barrier which might require all the so-called arts of courtship for its removal. Some criticisms bearing directly upon this aspect of the problem will be found in the life of the Marsh Warbler. Serious objections seem to me to stand in the way of its acceptance, but nevertheless it is the only modification of the theory which can in any way be made to correspond with the facts.

More space is devoted in the foregoing pages to emotional manifestation than to any other aspect of behaviour. Perhaps it is as well that it should be so, for we know little enough of the constitution of emotion or of the part it has to play in organic life, and only by minute observation, careful analysis, and comparison, can we hope to make any headway in the direction of a more complete understanding of the objective aspect of the subject. That each instinct has its corresponding emotion, as suggested by Dr. McDougall, seems to be true.