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 mayor. The influence of this early rivalry may be seen in several provisions of the existing city charter.

About 1840 a strong tide of immigration from Germany set in, continuing steadily for a half-century. It was greatly accelerated by the German revolutionary movements of the late 'forties, which added to the city’s population a considerable element of educated Germans of the upper class. From this time the Teutonic character of the population was marked. The first newspaper, the Advertiser, began publication in 1836; the first bank was established in 1837. In 1839 George Smith and Alexander Mitchell established the Fire and Marine Insurance Company Bank. As “Mitchell’s Bank” this institution was known for forty years as one of the strongest banking houses west of the Alleghanies, its notes passing at par during panics in which even the government issues were depreciated. Through it the Chicago Milwaukee & St Paul and other western railways were financed. Beer was first brewed in Milwaukee in 1840. Milwaukee was connected with Chicago by telegraph in 1849, and by railway in 1856. Previous to this, however, in 1851, the first train ran over the Chicago Milwaukee & St Paul railway to Waukesha, and in 1857 through trains were run over the same road to the Mississippi at Prairie du Chien.

 MIMETITE, a mineral consisting of lead chloro-arsenate, (PbCl)Pb4(AsO4)3, crystallizing in the hexagonal system and closely resembling (q.v.) in appearance and general characters. The arsenic is usually partly replaced by equivalent amounts of phosphorus, and there may thus be a gradual passage from mimetite to pyromorphite. The two species can, as a rule, only be distinguished by chemical analysis, and because of their close resemblance the less frequently occurring chloro-arsenate was named mimetite or mimetesite, from Gr. , imitator. Crystals of pyromorphite though usually optically uniaxial are sometimes biaxial, but in mimetite this anomalous character is almost always present; a cross-section of a hexagonal prism of mimetite shows a division into six optically biaxial sectors or a complex lamellated structure. In colour mimetite is usually yellow or brown, rarely white or colourless; the lustre is resinous to adamantine. The hardness is, and the specific gravity 7·0–7·25. Like pyromorphite, mimetite is found in the upper parts of veins of lead ore, where it has been formed by the oxidation of galena and mispickel. When found in large amount it is of importance as an ore of lead. The best crystallized specimens are those from Johanngeorgenstadt in Saxony and Wheal Unity in Cornwall. It was formerly found in considerable amount at Dry Gill in Cumberland, as six-sided barrel-shaped crystals of a brownish-red or orange-yellow colour and containing a considerable proportion of phosphoric acid; this variety has been called campylite, from Gr. , curved, on account of the remarkable curvature of the faces of the crystals.

 MIMICRY, in zoology, the deceptive and advantageous resemblance presented by defenceless and edible species of animals to other species of animals living in the same locality, which are harmful or distasteful and are consequently avoided by all or by a majority of the enemies of the class to which the mimetic and usually the mimicked species belong. Mimicry is a special form of protective resemblance, differing from ordinary protective resemblance as exemplified by the similarity of the resting goat-sucker to a piece of bark or of leaf- and stick-insects to the objects after which they are named, in that the imitated object belongs to the animal kingdom and not to the vegetable kingdom or to inorganic nature. Although, like protective resemblance, quite independent of affinity between the organisms concerned in the likeness, mimicry occurs most commonly between animals structurally similar, and therefore related, to one another, the relationship may be close or remote. For instance, the commonest and best-known cases are found in insects where

both mimic and model may belong to the same genus, sub-family, family or order, or to different orders. More rarely it occurs between members of distinct classes of the same sub-kingdom, i.e. between spiders and ants or spiders and beetles; yet even in this case both mimic and model have in common certain fundamental structural points to which the finishing touches completing the mimetic likeness are superadded. Still more rarely mimicry exists between totally unrelated species like caterpillars and snakes or spiders and snails. But in no case does it appear that the modifications in shape and colour, which contribute to bring about a mimetic resemblance, are greater and more elaborate than those which result in the simpler examples of ordinary protective resemblance.

The principle of protective resemblance, for which the term mimicry, as above defined, was originally employed, was first explained by H. W. Bates. Subsequently the meaning of the word was extended by F. Müller to include cases of mutual resemblance between two or more noxious species inhabiting the same area. Hence the resemblances belonging to the first category are commonly termed “Batesian mimicry,” and those belonging to the second category “Müllerian mimicry,” or more properly “Müllerian resemblance.” The difference between the two phenomena is essential and evident; but without experimental information as to palatability it is impossible to know with certainty to which of the two a particular case of mimicry is to be assigned. Over and over again extended knowledge on this point and inferences drawn from other facts have shown the certainty or probability of examples of mimicry being in reality “Müllerian,” which were previously accepted without question as “Batesian.” A simple illustration will serve to explain these two aspects of mimicry and to show the advantage in the struggle for existence that mimicry confers upon the species concerned.

There is a common English Syrphid fly (Eristalis tenax) known as the drone-fly from its resemblance to a large hive or honey bee. Honey bees are protected from a large number of insect enemies because they sting and are distasteful. Insect-eating birds soon learn to associate distastefulness with the size, form and colour of the bees, and consequently leave them alone after one or more trials. But flies of the drone-fly kind cannot sting, and, so far as is known, are perfectly innocuous and edible. The advantage to the fly of its deceptive resemblance to the bee is theoretically perfectly evident and practically can be demonstrated by experiment. It is in the first place a matter of common knowledge that human beings who have been taught to avoid handling bees invariably fear to touch drone-flies, unless specially trained to distinguish the one from the others. Moreover, Professor Lloyd Morgan found that young birds that had tasted and rejected workers of the hive bee as unpalatable subsequently refused to taste not only drones, which have no sting, but also drone-flies. So far as our information at present extends the resemblance between these two insects is a simple case of mimicry in the Batesian sense of the word. That is to say, an edible species is protected by resembling one that is inedible. But if it be discovered, as is possible, that the drone-fly is also inedible, the mimicry must be ascribed to the Müllerian category, and the reason for it becomes less evident. In what way, it may be asked, are two or more distasteful species of insects, occurring in the same locality, benefited by resembling each other? The ingenious explanation suggested by Fritz Müller for similar cases met with in butterflies is probably the true answer. This explanation depends upon what is now an experimentally demonstrated fact that insectivorous birds, and probably other animals, have no instinctive knowledge of what insects are edible and what inedible. This knowledge is acquired by experience; and since it is not, at all events as a rule, taught by the first taste to any individual bird, it is reasonable to infer that a considerable amount of injury, sufficient to disable if not to kill, is annually inflicted upon insects belonging to species protected by distastefulness or kindred qualities. Now insects that possess noxious attributes, and the same is true of other animals, usually have a conspicuous warning coloration which appeals to the eyes of enemies and helps them to remember more easily the cause of an 