DIPHTHEKIA. 271 DIPLOMA. changes in the nerves are of a degenerative char- acter, and quite similar to those found in neu- ritis from alcohol or other poisons. See Neu- BITIS. Toxin and Antitoxin. The diphtheria toxin has been isolated by Roux, Versin, Brieger, Fraenkol, and others, by lillration of cultures of the living bacilli through porous porcelain. While it has not yet been successfully analyzed, it appears to be analogous to the poisons of certain vononiou-; serpents. Fraenkel. Bchring. Wer- nicke, Aronson. Roux. anil others have succeeded in rendering annuals immune to diphtheria by the use of inoculations of virulent or somewhat attenuated cultures of diplithcria toxin. V. H. Park, of Xew York, says (in Twentieth Century Practice) : "Tlie most important and valuable results are those which have been obtained by Behring, in conjunction with others, who showed that tile blood of inniiune animals contains a substance which neutralizes the diplitheria toxin. The blood sermu of persons who liave recovered from diphtheri.a has also been found to possess this protective property, which it acquires about a week after the beginning of the disease, and loses again in a few months." To obtain antitoxin for therapeutic purposes, strong toxin obtained from virulent cultures of the Klebs-Liiffler bacil- lus is injected into the bodies of young, healthy horses. At the end of two months, during which time incrcasinf.' doses of the toxin have been given, blood is drawn from the horses ami tested for antitoxin. That havimj sufficiently strong antitoxin is retained and the process of inocu- lating and of withdrawing serum is repeated for years, allowing three months of each year as an interval of freedom from inoculations. The serum obtained is sterilized by the addition of carbolic acid by some who ]jrepare it, but Park considers the addition of any antiseptic as un- necessary and inadvisable. The antito.xie serum is used hypodermically as early as a diagnosis of diphtheria has been made, in dosage of from fiOO to 'JDOO units, a unit being equivalent to one cubic centimeter of "normal serum'; i.e. of blood serum of an immunized animal, which was made so eflicacious that 0.1 cubic centimeter an- tasronizfrs ten times the minimiuu of diphtheria poison fatal to a guinea-pig weighing 300 grams, or about ten oimces (.Jacobi, Tioentieth O'rntun/ Practice, vol. xvii., Xew York, 1898). See Antitoxin ; Bacteria ; Immunity ; and SeBIM THER.VPY. DIPHTHERIA (ix Fowls). See Kolt. DIPHTHERIA (in Pics). See Swine Plagix. DIPHTHONG (Lat. diphthontjus, Gk. 5l<t>- fvy-ios. fliiilillwnfjos, diphthong, from 5i-, dt-, dou- ble + <pe6r/yor,phthongos, sound, irom Kpdiyycaeai, phthpiiiiralhni, to utter). term used to denote two vowel sounds following one another so closely as to form but one syllable., as in out. In this combination the sound is really composed of an a as heard in father, and a u' as heard in put. The spelling of the English has little or no rela- tion to the pronunciation in this matter. In many syllables written with two vowels, only one sonnil is heard, as in hrend. The single vowel letters, again, often represent a diph- thnnt'al sound: thus, the long sonnd of i. as it is called, is really composed of the sound of a as heard in father anA that of e in me; and tune is pronounced as if written teun, or rather iyun. In such words as bread, field, the vowels, which are now monophthongs, were at one time real diphtliongs. and are still so pronounced in many parts of England ; on the other liand, many diphthongs in modern English are developed from original simple vowel sounds, or monoplitliongs; thus the ou in mouse is derived from the u of old Englisli i/iirs'. DIP'LOCOC'CUS. See Bacteria. DIPLOD'OCUS (Xeo-Lat., from Gk. SmXboc, diploos, double -f doK6(, dokos, beam ) . A gigan- tic fossil reptile of the order Dinosauria, sub- order Sauropoda, found in the .lurassic rocks of western Xorth America. Its body was long and low, its head remarkably small," its neck very long, trunk short and deep, and the tail was very long and quite thick at the base. The legs were strongly built and of almost equal length, indi- cating quadrupedal locomotion, and the feet were armed with heavy claws. The skull was high and laterally compressed posteriorly, with a long sloping face, and with large orbits situated far back on the sides. The jaws had weak, slender, spreading teeth only in their anterior portions, all the premolars and molars being absent. The vertebra- of Di])lodocus are of great interest be- cause of the elaborate systems of plates and but- tresses that give support to the vertebral pro- cesses and thus lend great strength without much increase of weight. The animal appears to have been herbivorous, and was probably aquatic, liv- ing in the extensive marshes and swamps of the Jurassic seas and lowlands that probably re- sembled those of the modem Amazon and Congo basins. Some figures, based upon the skeleton mounted in the Carnegie JIuseum at Pittsburg, express more clearly the immense proportions of this ancient reptile. The total length, from tip of nose to tip of tail, was about GO feet, and its height was nearly 12 feet. The head was 2 feet long, only one-tliirtieth of the length of the body, and the neck 20 feet in length. The trunk, from the point of the shoulder-blade to the middle of the sacrum, measured l.S feet, and had a depth of 7 to 8 feet, and the tail was at least 2.5 feet long. The animal is estimated to have weighed, when alive, about twenty tons, and to have required a daily meal of at least 500 pounds of vegetable food such as the twigs, leaves, and succulent stems of plants that grew in the waters of its habitat. Consult: Hatcher, '"Diplodocus, Marsh, Its Os- teolog}-, Taxonomy, and Probable Habits," Me- moirs of the Carnegie Museum, vol. i., No. 1 (Pittsburg, 1001) ; Lucas, Animals of the Past (Xew York. 1901). See I)inosauki.. DIPTLODTIS. See Pleuhacanthus. DIP'LOGRAPTUS. See Graptolite. DIPLOMA (Lat., from Gk. SlwXoi/ia, folded paper, letter of recommendation, from 5urX6of, diploo.i, double). . term used by tlie ancients especially to indicate letters of license received from the Ooveninicnt. It originated in the cus- tom of writing such documents on two tablets of wax which were doubled, or on writing material which was folded. Subsequently the term was applied to all old imperial and ecclesiastical acta and grants, public treaties, deeds, letters, wills, and all simihir instruments that were drawn up in a formal manner and marked with a seal or other peculiarities for idenliliciition. The term
