DICHROMATISM IN BIBDS. 214 DICKENS. fomis of clioctironmtism. known as oibinism. tne- lanism. and cnithrism. The lirst is that form in which <ine of the phases is wliite. and a number of examples oceiir aiiionj; the herons, as well as in other groups of birds. One of the best-known eases is that of the little blue heron (Ardca ctrnilat). some speiimens of which arc pure white, while others are slaty-b.ue. It was at one time supposed that the former were the young, the latter the adults; but careful study on their breeding grounds has shown that the dill'erences are not assixiated in any way with age or seN. Some evidence has been |)roduced to shoy that geographical conditions may have something to do with the matter, for the white birds are said to be most connnon on the Atlantic coast of Florida, while the colored phase is most abundant on the (Julf const. Melanism is a form of dichro- juatism in which one color phase becomes very dark, almost or quite black. Examples of this occur among the large hawks of the genus Butco. It should be .stated that in the.se cases the color phases are not sharply set otT from each other, as in the hercms. and llie melanism is closely asso- ciated with distribution. Erythrism is the form shown by the screeohowls, already referred to, in which one phase tends to become red. A satisfactory explanation of dichromatism 13 still to be olVeri'd. but reccut investigations have thrown some light upon it. In the screech-owl, the red phase is due to a -quantitative dilVerenee' m the distribution and relative amounts of pig- ment, and gray individuals may and do become red. In other cases, such as the herons, it is more than possible that we have examples of species in the process of formation, and that at some future dav the slaty-blue individuals of the little blue heron, for example, will breed only with slatv-blue individuals and produce only slatv-blue'offsnring. while the white birds will breed onlv with white birds and produce white young. We would then have just such a condi- tion as now exists in the ibises of the genus Gaura. The white ibis {Gaum alba) and the scarlet ibis (daiira nihra) are exactly alike, ex- cept for the striking dilTcrencc in color, but they never breed together and are therefore regarded as two distinct species, and not as dichromatic forms of one. The whole question is one of ex- ceptional interest, and seems to be closely bound up with that of the origin of species. DICHTtTNG UND WAHRHEIT, dlK'tyng vm viir'hit. SiM' GoLTUK. DICK, John (1764-183.3). A Scotch Seces- sion theologian. He became pastor in Glas- gow in 1801 and theological professor in 1820, and is remembered for his Lectures on Theology (4 vols., with memoir, 1834). DICK, Mr. A household abbreviation for Mr. Richard Dablcy, a demented character in Dick- ens's Darid <oppcrfichl. who Hies kites, jingles sovereigns, and has great difficulty in keeping the head of King Charles I. out of the 'Memorial.' DICK, Sir RoHERT IlENltY {c.l785-184(5). A Si'otih >oldicr. He served as an officer in the Pi-ninsula War. fighting at Uusaeo, Keuntes de Onoro, and Salaman<'a. He distinguished him- self at l.Uiatre Hras and Waterloo; in 1837 was promoted to 1m' major-general, and in 1841-42 was commander-in-chief at ^ladrns. In 184(1 he r.ssumed command of the Third Infantry Division in the Sikh War. He fell while leading a charge against the Sikh intrcuchiuents at the victory of Sobraon. DICK, TnoM.KS (17741857). A Scottish sci- ciitilic writer. He was born near Dundee, and studied science and theology at the Iniversity of Edinburgh. After a brief |)astoral charge in connection with the Secession Church of Scot- land, he devoted himself to teaching, lecturing, occasional ])reacliing, and authorship. Toward the close of his life a small pension was granted him in consideration of his literary services, his books having brought him very little pecuniary return, in spite of their great popularity both in England and the I'nited Slates. He died at Broughty Ferry, near Dundee. Dick's principal works a"re: The Chrislian Philosopher, or the Coiineetion of Science and Philosophy irith Re- ligion (1823; 8th ed. 1842); The Philosophy of Religion (1825): The Philosophy of a Future Stale (1828); Celestial Scenery (1837): The Sidereal Heavens (1840); and 77ie Practical Astronomer (1845). Several of Dick's writings have been translated into foreign languages: one even into Chinese. DICK BEQUEST. A fund now amounting to some £122.000. established in 1828 by .James Dick, of Finsbury Square, London, for the benefit of the parish sclioolmaslcrs of Moray, Banll. and Aberdeen, Scotland. These funds yield about £4000 a year, which is distributed as an honora- rium among the schoolmasters on the basis of their acquirements in the English language and literature, geography, mathematics, Latin, tireek, history, physics, aiid the art of teaching. Mr. Dick's object was to encourage active school- masters, and gradually to elevate the literary character of the i)aroehial schoolmasters and schools. His iiurpose has been so far successful that the grade of these .schools has bet>n advaneeil. and in many cases students go directly from them to the universities. DICK-CISSEL (imitative). The black- throated bunting {I-:uspi:a Americana) of the open regions of the central United States, one of the most pleasing of .merican fringilline birds. Its back is black, chestnut, and grayish; bend of the wing, bright chestnut: chin, white: throat, black, in a conspicuous crescent: breast, yellow, changing to white toward the tail. The female lacks the black breast-n-ark and the chestnut colors. The species is migratory, coming north- ward to make its nest on the grouml. or in a low bush, where pale-blue eggs are laid. It is a loud and persistent singer. "All day long," says Ridgway, "in spring and summer, the male.s, sometimes to the number of a dozen or more for each meadow of considerable extent, perch upon summits of tall weed-stalks or fence-stakes, at short intervals, crving out: 'See. sec— dick— dickcissel, cissel :' therefore 'Dick Cissel' is well known to every farmer's boy." Sec illustrations on Plates of BrNTl-MiS, etc.. and on Eggs, I. DICK^ENS, Ciiaki.es (1812-70). An English novelist. He was born at Landport, then a sub- urb of Portsmouth. His father. .Tohn Dickens, who held a post in the navy pay ofTice, was then stationed at Portsmouth, but about 1810 they moved to Chatham, and afterwards tr) Lon- don. The familv was poor and imjirovidcnt. The schooling of Charles wa.s slight, but he read considerablv at home and in the British Museum, and learned shorthand. He was e<lucated by
