place gradually, the ectoplasm growing as it stretches, or it may take place by the limiting layer of the ectosarc bursting, as it were, and a rounded prominence of the endosarc protruding and at once forming a new “skin” or pellicle. This last mode, termed “eruptive,” is common in the case of the enormous, multinucleate amoeba termed Pelomyxa palustris, which attains a diameter when contracted and spherical of as much as a line (over 2 mm.). From the ease with which amoebae are obtained and kept alive under the microscope, as well as from their identity in structure with the primitive elements of Metazoa, they have always been favourite objects of study for protoplasmic physiology under its simplest conditions. Among the investigators of protoplasmic movements we may cite F. Dujardin, O. Bütschli, L. Rhumbler and H. S. Jennings. The opening to the exterior of the contractile vesicle has been found here. Pelomyxa has yielded to A. E. Dixon and M. Hartog a peptic ferment, such as has been extracted by C. F. W. Krukenberg from the Myxomycete Fuligo (Flowers of Tan), which is the largest known naked mass of protoplasm without cellular differentiation.
Amoeba shows also the multiplication by fission, so characteristic of the cell: for the study of other modes of reproduction, spore formation and syngamic (or so-called fertilization) processes, fresh-water or salt-water amoebae are ill suited, and up to this date we do not know the life cycle of any free-living naked amoeba, though that of some parasitic forms and shell-bearers have been fully made out. Some amoebae are certainly young states of Myxomycetes. Encystment, the excretion of a membrane around the cell to tide over unfavourable circumstances, has been noted in almost all species.
Amoeba coli and A. histolytica are parasites in the gut of man, the former relatively harmless, the latter the cause of severe dysentery and hepatic abscess, common in India.
H. S. Jennings has recently made a full study of the movements of Amoeba, and of its general behaviour, and found therein many indications that these are on the whole such as we should expect of an organism working by “trial and error” rather than the uniform modes of non-living beings. Thus the operations of an amoeba ingesting a round, encysted Euglena are summed up thus: “One seems to see that the amoeba is trying to obtain this cyst for food, that it shows remarkable pertinacity in continuing its attempts to put forth efforts to accomplish this in various ways, and that it shows remarkable pertinacity in continuing its attempts to ingest the food when it meets with difficulties. Indeed the scene could be described in a much more vivid and interesting way by the use of terms still more anthropomorphic in tendency.” (M. Ha.)
AMOL, or Amul, a town of Persia, in the province of Mazandaran, 23 m. W. of Barfurush, in 36° 28′ N. Lat. and 52° 23′ E. long Pop. about 10,000. It is situated on both banks of the Heraz, or Herhaz river, which is crossed here by a very narrow stone bridge of twelve arches and flows into the Caspian Sea 12 m. lower down. Amol is not walled and is now a place of little importance, but in and around it there are ruins and ancient buildings which bear witness to its former greatness. Of these the most conspicuous is the mausoleum of Seyed Kavvam ud-din, king of Mazandaran, who died in 1379, and one old mosque dates from A.D. 793. The town has spacious and well-supplied bazaars and post and telegraph offices.
AMONTONS, GUILLAUME (1663–1705), French experimental philosopher, the son of an advocate who had left his native province of Normandy and established himself at Paris, was born in that city on the 31st of August 1663. He devoted himself particularly to the improvement of instruments employed in physical experiments. In 1687 he presented to the Academy of Sciences an hygrometer of his own invention, and in 1695 he published his only book, Remarques et expériences physiques sur la construction d’une nouvelle clepsydre, sur les baromètres, les thermomètres et les hygromètres. In 1699 he published some investigations on friction, and in 1702–1703 two noteworthy papers on thermometry. He experimented with an air-thermometer, in which the temperature was defined by measurement of the length of a column of mercury; and he pointed out that the extreme cold of such a thermometer would be that which reduced the “spring” of the air to nothing, thus being the first to recognize that the use of air as a thermometric substance led to the inference of the existence of a zero of temperature. In 1704 he noted that barometers are affected by heat as well as by the weight of the atmosphere, and in the following year he described barometers without mercury, for use at sea. Amontons, who through disease was rendered almost completely deaf in early youth, died at Paris on the 11th of October 1705.
’AMORA (Hebrew for “speaker” or “discourser”), a title applied to the rabbis of the 2nd to 5th centuries, i.e. to the compilers of the Talmud. Each tana—or rabbi of the earlier period—had a spokesman, who repeated to large audiences the discourses of the tana. But the ’amora soon ceased to be a mere repeater, and developed into an original expounder of scripture and tradition.
AMORITES, the name given by the Israelites to the earlier inhabitants of Palestine. They are regarded as a powerful people, giants in stature “like the height of the cedars,” who had occupied the land east and west of the Jordan. The Biblical usage appears to show that the terms “Canaanites” and “Amorites” were used synonymously, the former being characteristic of Judaean, the latter of Ephraimite and Deuteronomic writers. A distinction is sometimes maintained, however, when the Amorites are spoken of as the people of the past, whereas the Canaanites are referred to as still surviving. The old name is an ethnic term, evidently to be connected with the terms Amurru and Amar, used by Assyria and Egypt respectively. In the spelling Mar-tu, the name is as old as the first Babylonian dynasty, but from the 15th century B.C. and downwards its syllabic equivalent Amurru is applied primarily to the land extending northwards of Palestine as far as Kadesh on the Orontes. The term “Canaan,” on the other hand, is confined more especially to the southern district (from Gebal to the south of Palestine). But it is possible that the terms at an early date were interchangeable, Canaan being geographical and Amorite ethnical. The wider extension of the use of Amurru by the Babylonians and Assyrians is complicated by the fact that it was even applied to a district in the neighbourhood of Babylonia. If the people of the first Babylonian dynasty (about 21st century B.C.) called themselves “Amorites,” as Ranke seems to have shown, it is possible that some feeling of common origin was recognized at that early date.
AMORPHISM (from α, privative, and μορφἡ, form), a term used in chemistry and mineralogy to denote the absence of regular or crystalline structure in a body; the adjective “amorphous,” formless or of irregular shape, being also used technically in biology, &c.
AMORT, EUSEBIUS (1692–1775), German Catholic theologian, was born at Bibermühle, near Tölz, in Upper Bavaria, on the 15th of November 1692. He studied at Munich, and at an early age joined the Canons Regular at Polling, where, shortly after his ordination in 1717, he taught theology and philosophy. In 1733 he went to Rome as theologian to Cardinal Niccolo Maria Lercari (d. 1757). He returned to Polling in 1735 and devoted the rest of his life to the revival of learning in Bavaria. He died at Polling on the 5th of February 1775. Amort, who had the reputation of being the most learned man of his age, was a voluminous writer on every conceivable subject, from poetry to astronomy, from dogmatic theology to mysticism. His best known works are: a manual of theology in 4 vols., Theologia