126 DIONYSUS ical compositions as have been preserved have been published separately by Gross and by Westernmnn. There is an English translation of the "'Roman Antiquities, "by Ed ward Spel- raan (4 vols. 4to, London, 1758). DIONYSUS. See BACCHUS. DIOPHANTUS OF ALEXANDRIA, the only Greek writer on algebra, first mentioned by John, patriarch of Jerusalem, in the 8th century, un- less he bo identical with the astronomer Dio- phantus, on whose work Hypatia is said by Suidas to have written a commentary. There are no more definite indications of his era. When his MSS. came to light in the 16th cen- tury, thirteen books of his 'Apfffft^rutd were an- nounced, only six of which have been produced. Another treatise by him, Hepi ruv 'Apidfiuv Holv-yuvuv (" On Polygonal Numbers "), is ex- tant. These books contain a system of reason- ing on numbers with the use of general sym- bols, and are therefore algebraical treatises, though the demonstrations are written out at length in common language. The term Dio- phantine was applied by some modern mathe- maticians to the peculiar analysis employed in investigating the theory of numbers. The sim- ilarity of the Diophantine and Hindoo algebra renders it probable that they had a common origin, or that one was derived from the other. The best edition of his works is that of Fermat, in Greek and Latin (Toulouse, 1670). They were translated into German by Schulz (Ber- lin, 1821). The six books of the " Arithmetic " were translated into French by St6vin and Girard (Paris, 1625). DIOPTRICS. See OPTICS. DIOSCORIDES, Pedadns or Pedanios, a medical and botanical writer of the 1st or 2d century A. D., probably a native of Anazarbus in Cili- cia. lie made collections of plants in Asia Minor, Greece, Italy, and Gaul, and wrote a treatise in five books on materia medica (TLepi
- Y/b7f 'larpiKJjc), a work which enjoyed the
highest reputation until the 17th century. It is now chiefly valuable as illustrating the opin- ions of ancient physicians and giving some idea of tlu-ir attainments in natural history. It has been translated into Arabic, Italian* Spanish, French, and German, and many editions of it have been published in Latin and Greek. DIOSCURI. See CASTOR AND POLLUX. DIPHTHERIA (Gr. diQOtpa, membrane), the name of a disease which has heretofore re- ceived a variety of appellations, such as ulcus ^Egyptiacum vel Syriacum, cynanche maligna, ninjinii maligna, angina gangrcenosa, morfais mffocam nel strangulatorivs, garrotillo, an- gina supocativa, malignant sore throat, epi- demic croup, &c. The term diphtherite was applied to it by Bretonneau in 1821, whence originated the name diphtheria which is now i;i common use, relating to the formation of a false membrane in the throat and in other sit- uations, analogous to that which characterizes tin- disease called, among other names, diph- theritic laryngitis, or true croup. (See CEOUP.) DIPHTHERIA Recent microscopical observations, however, appear to show points of difference between the pseudo-membranous morbid product in the two diseases. In diphtheria the false membrane, accompanying inflammation, appears almost invariably in the fauces or throat, and in many cases it is limited to this situation. It may- extend more or less over the mucous surface within the mouth and nostrils. It is not in- frequently produced within the windpipe, giv- ing rise to all the symptoms of true croup, and generally proving fatal. Mucous surfaces else- where are in some cases the seat of this pecu- liar form of inflammation ; namely, in the eyes, the ears, the organs of generation, &c. A sim- ilar false membrane is produced in some cases on the skin, in situations where there may be either wounds, abrasions, or sores. The local affections thus characterized cannot be said to constitute the disease, but they are to be considered as the manifestations of a morbid condition of the system, probably involving special blood changes, the essential nature of which is at present unknown. In other words, diphtheria belongs among the diseases which are distinguished nosologically as general or constitutional. The disease rarely occurs ex- cept as an epidemic. Epidemic diphtheria has occurred in all countries, but in the United States only occasional sporadic cases were ob- served during the first half of the present cen- tury. Since about 1856, however, there have been repeated epidemics in different parts of the country. "Whether it be one of the com- municable diseases, that is, diffused by con- tagion or infection, is an open question. Per- sons between 3 and 12 years of age are most apt to be affected with it, but no period of life is exempt from a liability to it. The false membranes are found frequently to contain a parasitic fungus, the spores and sporules of a cryptogamic plant ; and the idea has been en- tertained that the disease is due to the pres- ence of these. It seems, however, more rea- sonable to suppose that they are merely inci- dental to the local affection, the morbid pro- ducts furnishing only a proper nidus or soil for their growth and reproduction. Different epi- demics differ much in the rate of mortality. The disease is sometimes mild, the local mani- festation being confined to the throat, and the constitutional symptoms slight. In other cases it has a degree of violence and a fatal tendency which entitles it to be classed among the ma- lignant diseases. Death sometimes takes place within 48 hours after the attack. The degree and extent of local manifestations are in gen- eral commensurate with the severity and dan- ger. If the larynx becomes affected, the chances of recovery are very few. Frequent vomiting, diarrhoea, hremorrhage from the nostrils or elsewhere, frequency and feebleness of the pulse, convulsions, delirium, and coma are symptoms which denote great danger. If the larynx is affected, death may take place from suffocation. In the fatal cases in which the
