HEBB. 800 least, none above the ground. Herbaceous plants commonly die down to the ground at the close of tile growing season. In some herbaceous plants, such as annuals, the entire plant dies during the resting period. HEKBA'RIUM ( Lat.. from 7,fr6o, Jierb) . A systematic cullectiun of dried plants, representing the llora of one or more regions. An herbarium represents the best possible record of plants, and IS indispensable as a basis for any systematic presentation of a flora. Of course, "the study of hvmg plants in their natural surroundings is the ideal metliod, and is employed as far as possible. But such a method is "necessarily in- complete, and must be supplemented by the com- plete records of the herbarium. One of the essential features of an herbarium is that it con- tains the specimens, called 'types,' from which the original descriptions of species and "cne'-a ^vere drawn. These types are kept for reference, so that there may be no uncertainty as to the plants described by diflferent autho"rs- and it may be said that, in a certain sense, the value of an herbarium is measured bv the number of types and authentic specimens it" contains. Largo herbaria tluis become centres of taxonomic work Owing, however, to the great expense involved m maintaining them, extensive herbaria are not numerous; the local collections possessed bv a large number of institutions and individuals "are generally quite small. In the United States there are three herbaria of first rank, and each is the background of con- tinual publication. The oldest is the Graij Her- hariiim. which belongs to Harvard University Its great value lies in the fact that it contains the vast majority of the older tvpes of American plants, but its annual additions are also verv large. The Hcrhnriiim of the .A'cr York Botnnknl Garden, formerly at Columbia Universitv, was developed remarkably during the closing years of the nineteenth century. Its accumulation of mate- rial and wealth of types makes it indispensable in any taxonomic work. The United fftates Na- tional Herhariiim, stored in the United States National Jruseum. has become a collection of national importance, since it contains a vast accumulation of material brought together bv Government collectors, and also manv of the most important collections of the" earlv" Government surveys. After these three great collection' those at the Missouri Botanical Garden (Saint Louis) and at the Field Columbian Museum (Chicago) are iirobably next in importance. Many of the larger universities also contain note- worthy collections. The three greatest herbaria in Europe deal more with the flora of the whole world than do the American herbaria. The greatest of all herbarium collections is that at the Royal Gardens at Kew, which has been en- riched for many years by means of the numerous colonial enterprises of the British Empire. Thj Eerharium of the Jardin des Plantcs at Paris is rich in older types, especially of American plants. The University of Berlin'has built up a large herbarium, which has become one of first importance. Probably next in importance are the herbaria at Geneva, Vienna, and Saint Peters- l)urg. For directions as to the collection of plants and their preparation for the herbarium, consult Bailey, Botanizinp (Providence, R, I., 1899). HEE.BART. n"r"^?,fi^^ '/i^'"""'^' JOHANN FlilEDRICH (iul.-1841). A German philosopher. He was born at Oldenburg, May 4, 177U. He studied at Jciia, where Fichte was just beginning to be an influential factor m the universitv life, and for a while he was ardent in his loyalty to Fichte's views; but after more reflection he found him.self obliged to reject much of that system, and to form one of his own. After tutoring for several years in Switzerland, he qualified as doceiit in Jilulosophy and pedagogj- at Gottingeii in 1802 and three years later was appointed professor extraordinarius. In 1809, at the instance of W on Humboldt, then at the head of the Depart- ment of Public Instruction, he was called to a professorship of philosophy and pedagogy at Kij- nigsberg, to succeed Krug. who succeeded Kant As in Gbttingen, he conducted a seminar at Kci- nigsberg: but in IS.SS he was recalled to Gottin- geii. yheie he continued in incessant pedagogical and philosophical activity until his death, August 14 1841. His writings were collected and imb- lished by Hartenstein in 12 volumes (Leipzi<r ISoO). and reprinted in Hamburg (13 vols., 1883- 93 ) . Another edition is appearing at Langensalza. liis pedagogical works have been published in two volumes at difi'erent times ( 1873. 1875, and 1880) Some of his letters were published in 1871 and in 1877. His chief works are: AUr/cmeine Pudaqogik (1806); Hauptpiinkte der iletaphi/sik (1806)- Allfjemeine praktisehe Philosophie ('l80S) ; Lehr- Inch ^iir Ei)ilcitun(i in die Philosophic (1813) ■ Lehrbuch zur Psychologie (1816; translated into English by M. K. Smith. 1891) ; Psi/chologie als ] issenschaft (1824); Allgemeine Metaphysik (1828-29). In addition to the one mentioned above, the following translations should be men- tioned: Application of Pxi/chohxn/ to the Science of Education, translated by Jlulii'ner (New York, 1898) : Herhart's ABC of Sense-Paxeption, and Minor Pedagogical Works, translated by Eckoff (lb., 1896) ; The Science of Education, translated by H. M. and E. Filkin (Boston, 1893) ; Intro- duction to the Pedagogi/ of Hcrbart, translated by Zimson (ib., 1894); Outlines of Educational Doctrine, translated by Lange, and annotated by De Garmo (New York, 1901). His philosophy is a thorough-going atomism (q.v.), according to which the universe is consti- tuted of monads or 'reals,' simple, unchangeable, and in their real nature unknowable. These •reals' stand in accidental relations to each other, and it is the changes in these relations that con- stitute the process of change in the -world of ex- perience. The 'reals' disturb each other and pro- voke reaction in each other in self-defense. Such reactions are our ideas, which are called for by the eflfort of our unknowable souls to maintain themselves. These ideas in turn tend to preserve themselves, and conscious life is the behavior of these ideas toward each other in the way of con- flict or of mutual support — conflict when they are totally or partially opposed; support wheii they are alike. When conflict occurs, the inten- sity of ideas is diminished; diminution of in- tensity beyond a certain point means the disap- pearance of ideas 'below the threshold of con- sciousness.' The relation between ideas is thus a mechanical relation and p.svchnlogy is the me- chanics of ideas. In the mechanical relation of ideas, those already in consciousness have an im- portant part to play with regard to new ideas just appearing. The ideas already present are
