It may, however, be argued that it is not when at rest but during flight that the mimetic resemblance protects the mimic from attack. Actually this can hardly be true, for the mode of flight constitutes one of the most striking differences between model and mimic. _P. hector_ and _P. aristolochiae_ fly much in the same way. They give one the impression of flying mainly with their fore wings, which vibrate rapidly, so that the course of the insect, though not swift, is on the whole sustained and even. The flight of all the different forms of _polytes_ is similar and quite distinct from that of the models. It is a strong but rather {83} heavy and lumbering up-and-down flight. One gets the impression that all the wing surface is being used instead of principally the fore wings as appears in _P. hector_ and _P. aristolochiae_. The difference is difficult to put into words, but owing to these peculiarities of flight the eye has no difficulty in distinguishing between model and mimic even at a distance of 40 to 50 yards. Moreover, colour need not enter into the matter at all. It is even easier to distinguish model from mimic when flying against a bright background, as for instance when the insect is between the observer and a sunlit sky, than it is to do so by reflected light. I have myself spent many days in doing little else but chasing _polytes_ at Trincomalee where it was flying in company with _P. hector_, but I was never once lured into chasing the model in mistake for the mimic. My experience was that whether at rest or flying the species are perfectly distinct, and I find it difficult to imagine that a bird whose living depended in part upon its ability to discriminate between the different forms would be likely to be misled. Certainly it would not be if its powers of discrimination were equal to those of an ordinary civilised man. If the bird were unable to distinguish between say the A form of female and _P. aristolochiae_ I think that it would be still less likely to distinguish between the same A form and the male or the M form of female. For my experience was that at a little distance one could easily confuse the A form of _polytes_ with the male. Except when one was quite close the red on the A form was apt to be lost, the {84} white markings on the hind wing were readily confused with those of the male, and one had to depend entirely on the lighter fore wing. Unless the bird were keener sighted than the man the A form would be more likely to be taken in mistake for its unprotected relative than avoided for its resemblance to the presumably unpalatable model. On the other hand, if the bird were sufficiently keen sighted never to confuse the A female with the male form its sight would be too keen to be imposed upon by such resemblance as exists between the A female and _P. aristolochiae_.