M E R M E R 35 Calomel ointment is not irritating, but rather tends to soothe. It is therefore sometimes applied to irritable rashes ; in pruritus ani it is of special value. Mercurial preparations are not usually found of benefit in scaly eruptions. In acne a weak solution of corrosive sublimate is often most effective. Preparations of mercury are often used to heal ulcers, e^pecially those of syphilitic origin. Black wash is one of the commonest applications for this purpose. The red oxide ointment is at times employed to stimulate indolent ulcers, and it is capable of remov ing exuberant granulations (proud flesh), which sometimes retard the healing of wounds. Mercury is largely used externally to promote the absorption of inflammatory products, especially in the neighbourhood of joints. The blue ointment is frequently employed for this purpose, more rarely a plaster containing mercury or a mercurial liniment. For effecting the absorption of goitre (Derbyshire neck) the ointment of the red iodide is often relied on, especially in India, where it is customary to expose the patient s neck to the sun after rubbing it with the ointment. In enlargements of the liver and spleen the application of mercurial ointment sometimes seems to promote re duction in size. Taken internally in continued doses, mercury produces a peculiar effect known as salivation. First a metallic taste is experienced ; this is followed by soreness of the gums, an undue flow of saliva, and foetor of the breath. Further administration of the drug may increase greatly the salivary flow, and also lead to swelling of the tongue, ulceration of the mouth, and even disease of the jaw-bone. At the same time the blood becomes impoverished, and feverishness with loss of flesh occurs. A single large dose rarely too a single small dose may produce some of the above symptoms. They may also follow the inhalation of the metal or it s compounds, or their absorption through the skin. The long-continued inhalation of the vapour of mercury acts likewise on the nervous system, caus ing a peculiar kind of trembling. Mercurial tremor is sometimes seen in looking-glass makers, often in those who work in quick silver mines. Internally mercury is chiefly given for two purposes (1) to check inflammation and cause the absorption of the products it gives rise to, and (2) to antagonize the syphilitic virus and remove the evils it causes. Some years ago the belief in the power of mercury to control inflammation was almost universal, and it was largely administered in almost all inflammatory affections, but of late it has been much less used, both because it seems doubtful whether it has really the power it was once supposed to have and because of the possibility of evil results from its continued use. In peritonitis and iritis it is still often employed, small doses of calomel being given. Not unfrequently too it is administered in pericarditis and hepatitis, but in pneumonia, pleurisy, and most other inflammatory affections its use is now discarded by many physicians. As an antidote to the syphilitic poison it is still held in high esteem, though opinions vary much as to the extent of its power. There can be little doubt that, given in an early stage of the disorder, it minimizes the secondary symptoms ; but it cannot be relied on to prevent their occurrence. It aids in removing the secondary symptoms, and tends to the avoidance of tertiary manifestations, which nevertheless sometimes occur even when mercury has been freely given. The custom of giving mercury till profuse salivation is established has long been abandoned ; the aim now is so to give it as to prevent salivation occurring ; for this purpose blue pill, calomel, and corrosive sublimate are given in very small doses, but if the gums become tender the dose is decreased or the administration stopped. Mercurial treatment is sometimes carried out by rubbing the blue ointment into the skin, sometimes by exposing the patient to the fumes of calomel ; syphilitic eruptions are often treated by such fumigation. More rarely mercury is introduced by injecting the alburninate or some other preparation under the skin or by means of suppositories. In children grey powder is generally used when mer curial treatment is required. Children bear mercury well. Blue pill, calomel, and grey powder are often used as purgatives, and a power of promoting the secretion of bile is attributed to them. Experimentally it has not been proved that they stimu late the liver functions, but there is good reason for believing that they promote the expulsion of bile from the body. Grey powder is especially valued as a mild and efficient aperient for children, and is often given in the early stage of diarrhoea to expel the irritating contents of the bowel. The use of calomel in tropical dysentery, once very prevalent, has within the. last few years been abandoned. (D. J. L. ) MERGANSER, a word originating with Gesner (Hist. Animalium, iii. p. 129) in 1555, and for a long while used in English as the general name for a group of fish-eating Ducks possessing great diving powers, and forming the genus Mergus of Linnaeus, now regarded by ornithologists as a Subfamily, Merging, of the Family Anatidse. The Mergansers have a long, narrow bill, with a small but evident hook at the tip, and the edges of both man dibles beset by numerous horny denticulations, whence in English the name of " Saw-bill " is frequently applied to them. Otherwise their structure does not much depart from the Anatine or Fuliguline type. All the species bear a more or less developed crest or tuft on the head. Three of them, Mergus merganser or castor, M. serrator, and M. alhellus, are found over the northern parts of the Old World, and of these the first two also inhabit North America, which has besides a fourth species, M. cucullatus, said to have occasionally visited Britain. M. merganser, commonly known as the Goosander, is the largest species, being nearly as big as the smaller Geese, and the adult male in breeding-attire is a very beautiful bird, conspicuous with his dark glossy-green head, rich salmon-coloured breast, and the upper part of the body and wings black and white. This full plumage is not assumed till the second year, and in the meantime, as well as in the post nuptial dress, the male much resembles the female, having, like her, a reddish-brown head, the upper parts greyish- brown, and the lower dull white. In this condition the bird is often known as the " Dun Diver." This species breeds abundantly in many parts of Scandinavia, Russia, Siberia, and North America, and of late years has been found to do so in Scotland, usually making its nest in the stump of a hollow tree or under a slab of rock. M. serrator, com monly called the Red-breasted Merganser, is a somewhat smaller bird ; and, while the fully-dressed male wants the delicate hue of the lower parts, he has a gorget of rufous mottled with black, below which is a patch of white feathers, broadly edged with black. The male at other times and the female always much resemble the preceding. It is more numerous than the Goosander, with a somewhat more southern range, and is not so particular in selecting a sheltered site for its nest. Both these species have the bill and feet of a bright reddish-orange, while M. albellus, known as the Smew, has these parts of a lead colour, and the breeding plumage of the adult male is white, with quaint crescentic markings of black, and the flanks most beauti fully vermiculated the female and male in undress having a general resemblance to the other two already described but the Smew is very much smaller in size, and, so far as is known, it invariably makes its nest in a hollow tree, as ascertained first by Wolley (Ibis, 1859, pp. 69 et seq.}. This last habit is shared by M. cucullatus, the Hooded Merganser of North America, in size intermediate between M. albellus and M. serrator, the male of which is easily recognizable by his broad semicircular crest, bearing a fan- shaped patch of white, and his elongated subscapulars of white edged with black. The conformation of the trachea in the male of M. merganser, M. serrator, and M. cucullatus is very like that of the Ducks of the genus Clangula, but M. albellus has a less exaggerated development more resembling that of the ordinary Fuligula. 1 From the southern hemisphere two species of Mergus have been described, M. octosetaceus or brasilianus, Vieillot (N. Diet. d Hist. Naturelle, ed. 2, xiv. p. 222 ; Gal. des Oiseaux, 1 Hybrids between, as is presumed, M. albellus and Clangula ylaucion, the common Goklen-eye, have been described and figured (Eimbeck, I sis, 1831, SCO, tab. iii. ; Brehm, Naturgesch. aller Vog. Deutschlands, p. 930 ; Naumann, Vog. Deutschlands^ xii. p. 194, frontispiece ; Kjrerbolling, Jour, fur Ornithologie, 1853, Extraheft, p. 29, Naumannia, 1853, p. 327, Ornithol. Danica, tab. lv., suppl. tab. 29) under the names of Mergus anatarius, Clangula angustirostris, and Anas (Clangula] mergoides, as though they were a distinct species ; but the remarks of M. de Selys-Longchamps (Bull. Ac. Sc. Bruxdles, 1845, pt. ii. p. 354, and 1856, pt. ii. p. 21) leave little room for doubt as to their origin, which, when the cryptogamic habit and common range of their putative parents, the former unknown to the author last-
named, is considered, will seem to be still more likely.