Panmixia

“ As soon, therefore, as the immortality of somatic [body-] cells became useless, they would begin to lose this attribute." [CN] Even granting that panmixia could continuously reduce the size of ducks' wings, it is not easy to see how it could get rid of immortality. The essence of the idea of panmixia is that, when the natural selection which has raised an organ to a high functional level, and sustains it there, ceases or is suspended, the organ drops back from its high level. But on Professor Weismann's hypothesis, immortality has neither been produced nor is it sustained by natural selection. ”

“ All are agreed that natural selection alone is insufficient to explain all, if any, of the processes of degeneration. All either consciously or not admit the principle of panmixia, and all are now agreed that this process alone can not produce extensive degeneration. All are agreed that the important point is degeneration beyond the point reached by panmixia, the establishment of the degenerating process, whatever it may be, in the germ, or, in other words, the breaking of the power of heredity. ”

“ He failed to adequately notice the effect of panmixia, or the withdrawal of selection, in causing or allowing degeneracy and dwindling under disuse; and he hardly attached sufficient importance to the fact that rudimentary organs and other supposed effects of use or [49] disuse are quite as marked features in neuter insects which cannot transmit the effects of use and disuse as they are in the higher animals. ”

“ Romanes has not shown that when natural selection ceases to act on an organ the minus variations in each new generation will exceed the plus variations. But if they are equal the alleged process of panmixia has no place. ”

“ Panmixia steps in, i. e., selection ceases to influence these organs. Individuals with large and individuals with small hind legs are equally favored in the struggle for existence.
From this fact alone would result a degradation of the organ, but of course it would not be very marked in extent, seeing that the minus variations which occur are no longer removed. According to our assumption, however, such minus variations repose on the weaker determinants of the germ, that is, on such as absorb nutriment less powerfully than the rest. ”

“ This is undoubtedly true, as Romanes pointed out ten years before I did, and this mingling of the bad with the good probably does bring about a deterioration of the part concerned. But it cannot account for the steady diminution, which always occurs when a part is in process of becoming rudimentary, and which goes on until it ultimately disappears altogether. The process of dwindling cannot therefore be explained as due to panmixia alone; we can only find a sufficient explanation in germinal selection. ”

“ The transition between conditions of possible use and absolute disuse may have been rapid with each individual after permanently entering a cave. Panmixia, as regards the minute eye, continued. Reversed selection, for economy, can not have affected the eye for reasons already stated. The mere loss of the force of heredity, unless this was caused by disuse, or the process of germinal selection, can not have brought about the conditions, because some parts have been affected more than others. ”

“ Nor is the degeneration stopped by the uninterrupted crossing of individuals in sexual propagation, but only slightly retarded. The number of individuals with weaker determinants must, despite this fact, go on increasing from generation to generation, so that soon every determinant that still happens to be endowed with exceptional vigor will be confronted by a decided overplus of weaker determinants, and by continued crossing therefore will become more and more impoverished. Panmixia is the indispensable precondition of the whole process ”

“ The result of Panmixia in finger markings, corroborates the arguments I have used in Natural Inheritance and elsewhere, to show that “organic stability” is the primary factor by which the distinctions between genera are maintained; consequently, the progress of evolution is not a smooth and uniform progression, but one that proceeds by jerks, through successive “sports” (as they are called) , some of them implying considerable organic changes, and each in its turn being favoured by Natural Selection. ”

“ It is still open to us to consider whether there are any cases in which the inheritance of acquired modifications is a more probable hypothesis than the selection of favourable germinal variations. Now, the acquisition of an instinctive dread of man, and the loss of this instinctive timidity under domestication, seem to be of this kind. And yet I doubt whether the evidence on this head is convincing. For the loss of instinctive timidity, Professor Weismann may invoke the aid of panmixia. ”

“ They cannot exercise the slightest influence on marriage selection, the very existence both of the ridges and of the patterns having been almost overlooked; they are too small to attract attention, or to be thought worthy of notice. We therefore possess a perfect instance of promiscuity in marriage, or, as it is now called, panmixia, in respect to these patterns. We might consequently have expected them to be hybridised. But that is not the case; they refuse to blend. Their classes are as clearly separated as those of [Pg 210] any of the genera of plants and animals. ”

“ It is evident that a large, really extravagant development of the eye in such a fish as Chologaster would not effect the removal of the individual by personal selection; still less so in Amblyopsis, which not only lives in comparative abundance, but has lived for twenty months in confinement without visible food, and in which the eye is minute. It seems that all the admitted objections to degeneration by panmixia apply with equal402 force to germinal selection. ”

“ Darwin's argument is based on the changed ratio between the weights of leg-bones and wing-bones, and that this changed ratio may result not from decrease of the wing-bones but from increase of the leg-bones, then there comes a fatal reply. Such, increase cannot be ascribed to selection of varieties, since there is no selective breeding to obtain larger legs, and as it is not pretended that panmixia accounts for increase the case is lost: there remains no cause for such increase save increase of function. ”

“ VII, figs. 6 and 7) shews a similar difference in the sexes, the male and female of this species mimicking respectively the male and female of Planema macarista. The case is made even more remarkable by the fact that both of the sexual forms of Planema macarista are mimicked by the Satyrine Elymnias phegea (Pl. VII, fig. 9) , though in this species either the black and white, or the black, white, and orange form may occur in either sex. Among the best Papilionine mimics of the Planemas is Papilio cynorta whose female is extraordinarily like the common Planema epaea (Pl. VII, figs. 5 and 10) . ”

“ However, this evening Phanis doesn't see them.
He's in such a state that he remembers a thousand and one things. They come to mind all at the same time: the games he played, the courses he had last year, a fruit he cut and ate when he was little; a nest he'd found... Everything coming and going in his head, like ants in a nest. His head is buzzing.
His eyelids are burning and swollen. He really wants to sleep.
At last sleep came. This time it was deeper. Phanis will have slept for at least five or six hours. He felt in his sleep that he was cold, but he couldn't get up. ”

“ It seems not unreasonable to conjecture that the uniformly high physical standard of the Punans and their seemingly exceptional immunity from disease are due to their exposed mode of life, and to the consequently severe selection exercised upon them by their environment. ”

“ To trace the original origin of Pantomime, or Mimicry, we must go to Nature herself where we can find this practised by her from the beginning of all time as freely, and as fully, as ever it was, or ever will be, upon the stages of our theatres. What better evidence, or instances, of this can we have than in those studies of her handiwork? as the larger species of caterpillars, when, by stretching themselves out in imitation of, and to make their foes think that they are snakes ”

“ Africa has a group of models not found in Asia, and the Papilio-Danaine series is as it were curtailed by the Papilio-Planema series with which to some extent runs parallel the genus Pseudacraea. These phenomena of parallel series have been mentioned here as shewing that mimicry tends to run in certain groups and that in many cases at any rate little meaning can be attached to the statement that the imitators differ from the bulk of their allies. ”

“ To expiate the abominable sin of his dream, and flee from impure thoughts, Paphnutius determined to leave his cell, which had now become polluted, go far into the desert, and practise unheard-of austerities, strange labours, and fresh works of grace. But before putting his design into action, he went to see old Palemon and ask his advice.
He found him in his garden watering his lettuces. It was the evening. The blue Nile flowed at the foot of violet hills. The good old man was walking slowly, in order not to frighten a pigeon that had perched on his shoulder. ”

“ Something not unlike the huge Pantomime masks of a hideous and frightful shape that we sometimes see in our present day Pantomimes must have appeared, especially those that covered the head and shoulders of the Mimis in the days of the Romans. Those that were just of the size of the face in all probability were fantastic and picturesque; and the third and remaining species of mask made of a transparent substance could hardly have been very effective. ”

“ Mimetics only. The males are in all cases alike to look at but it must nevertheless be supposed that they differ in their transmitting powers. In fact the evidence all points to there being three different kinds of male corresponding to the three different kinds of female. But they cannot shew any difference outwardly because there is always present in the male a factor which inhibits the production of the mimetic pattern even though the factor for that pattern be present. ”

“ The spots of Pansydia are smaller and far less conspicuous than in Pamphilites, that of the cell being reduced almost to a dot; the median spots are however large, though removed farther from the base, as in Carystus; there is also a small spot in the upper median interspace, but further from the margin than in Pamphilites and unaccompanied by any spot in the interspace beyond the cell; as in Carystus, the spot surmounting the submedian nervure is further from the outer margin than in Pamphilites, but the subcostal spots accord very well with those of the fossil. ”

“ He blasphemed against the gods, and threw himself amongst the assailants, behind whom the beggars crawled, shaking their crutches. Paphnutius was soon enclosed in a circle of menacing fists, raised sticks, and cries of death.
“To the ravens with the monk! to the ravens!”
“No; throw him in the fire! Burn him alive!”
Seizing his fair prey, he pressed her to his heart.
“Impious men,” he cried in a voice of thunder, “strive not to tear the dove from the eagle of the Lord. But rather copy this woman, and like she turn your filth into gold. ”

“ Of the total number of mimicry instances a high proportion is supplied by relatively few groups. In each region several main series of models and mimics run as it were parallel to one another. In Asia, for example, we have the Papilio-Danaine series where the colour-patterns of a series of Danaines, all nearly related, are closely paralleled by those of a section of the genus Papilio, and by those of the Satyrid genus Elymnias. In Africa there is a similar Papilio-Danaine series though of less extent. ”

“ That the imitative species occur in the same area and occupy the very same station as the imitated.
This on the whole is generally true. It is well shewn in some of the most striking cases such as those of the Old-World Papilios that mimic Danaines, or of the Dismorphias and their Ithomiine models. In many of these cases the range of neither model nor mimic is a very wide one, yet the mimic is found strictly inside the area inhabited by the model. Papilio agestor, for instance, is only found where Caduga tytia occurs, nor is P. mendax known outside the area frequented by Euploea rhadamanthus. ”

“ Most butterflies rest with their wings closed. In many of the well-known cases of mimicry the pattern on the under surface of the mimic's wings which would meet the monkey's eye is quite different from that of its model. It is difficult in such cases to imagine the monkey operating as a factor in establishing a resemblance between the upper surfaces of the wings of the two unrelated species. ”

“ It was therefore not astonishing that Paphnutius knew at once that the vision which had visited him in his sleep was an evil one.
Whilst he was gently remonstrating with God for having given him into the power of the demons, he felt himself pushed and dragged amidst a crowd of people who were all hurrying in the same direction. As he was unaccustomed to walk in the streets of a city, he was shoved and knocked from one passer to another like an inert mass; and being embarrassed by the folds of his tunic, he was more than once on the point of falling. ”