the journal, Beiträge zur Biologie, which he then started (1870–1871), and which has since become so renowned. Investigations on other branches of bacteriology soon followed, among which “Organismen der Pockenlymphe” (1872) and “Untersuchungen über Bacterien” (1872–1875) are most important, and laid the foundations of the new department of science which has now its own laboratories, literature and workers specially devoted to its extension in all directions. When it is remembered that Cohn brought out and helped R. Koch in publishing his celebrated paper on Anthrax (1876), the first clearly worked out case of a bacterial disease, the significance of his influence on bacteriology becomes apparent.
Among his most striking discoveries during his studies of the forms and movements of the Bacteria may be mentioned the nature of Zoogloea, the formation and germination of true spores—which he observed for the first time, and which he himself discovered in Bacillus subtilis—and their resistance to high temperatures, and the bearing of this on the fallacious experiments supposed to support abiogenesis; as well as works on the bacteria of air and water, the significance of the bright sulphur granules in sulphur bacteria, and of the iron oxide deposited in the walls of Crenothrix. His discoveries in these and in other departments all stand forth as mementoes of his acute observation and reasoning powers, and the thoughtful (in every sense of the word) consideration of the work of others, and suggestive ideas attached to his principal papers, bear the same characteristics. If we overcome the always difficult task of bridging in imagination the interval between our present platform of knowledge and that on which bacteriologists stood in, say, 1870, we shall not undervalue the important contributions of Cohn to the overthrow of the then formidable bugbear known as the doctrine of “spontaneous generation,” a dogma of despair calculated to impede progress as much in its day as that of “vitalism” did in other periods. Cohn had also clear perceptions of the important bearings of Mycology and Bacteriology in infective diseases, as shown by his studies in insect-killing fungi, microscopic analysis of water, &c. He was a foreign member of the Royal Society and of the Linnean Society, and received the gold medal of the latter in 1895. He died at Breslau on the 25th of June 1898.
Lists of his papers will be found in the Catalogue of Scientific Papers of the Royal Society, and in Ber. d. d. bot. Gesellsch., 1899, vol. xvii. p. (196). The latter also contains (p. (172)) a full memoir by F. Rosen. (H. M. W.)
COHN, GUSTAV (1840– ), German economist, was born on the 12th of December 1840 at Marienwerder, in West Prussia. He was educated at Berlin and Jena universities. In 1869 he obtained a post at the polytechnic in Riga, and in 1875 was elected a professor at the polytechnic at Zürich. In 1873 he went to England for a period of study, and as a result published his Untersuchungen über die englische Eisenbahnpolitik (Leipzig, 1874–1875). In 1884 he was appointed professor of political science at Göttingen. Cohn’s best-known works are System der Nationalökonomie (Stuttgart, 1885); Finanzwissenschaft (1889); Nationalökonomische Studien (1886), and Zur Geschichte und Politik des Verkehrswesens (1900).
COHOES, a city of Albany county, New York, U.S.A., about 9 m. N. of Albany, at the confluence of the Mohawk and Hudson rivers. Pop. (1890) 22,509; (1900) 23,910, of whom 7303 were foreign-born; (1910) 24,709. It is served by the New York Central & Hudson River and the Delaware & Hudson railways, by electric lines to Troy and Albany, and by the Erie and Champlain canals. It is primarily a manufacturing city. Hosiery and knit goods, cotton cloth, cotton batting, shoddy, underwear and shirts and collars are the principal products, but there are also extensive valve works and manufactories of pulp, paper and paper boxes, beer, pins and needles, tools and machinery, and sash, doors and blinds. The value of the factory products in 1905 was $10,289,822, of which $4,126,873, or 40.1%, was the value of hosiery and knit goods, Cohoes ranking fifth among the cities of the United States (of 20,000 inhabitants or more) in this industry, and showing a higher degree of specialization in it than any other city in the United States except Little Falls, N.Y. The Falls of the Mohawk, which furnish power for the majority of the manufacturing establishments, are 75 ft. high and 900 ft. broad, a large dam above the falls storing the water, which is conveyed through canals to the mills. Below the falls the river is crossed by two fine iron bridges. The city has a public library, a normal training school and the St Bernard’s (Roman Catholic) Academy. Cohoes was a part of the extensive manorial grant made to Killian Van Rensselaer in 1629 and it was probably settled very soon afterwards. It was incorporated as a village in 1848 and was chartered as a city in 1870.
COHORT (Lat. cohors), originally a place enclosed: in the Roman army, the name of a unit of infantry. The troops of the first grade, the legions, were divided into cohorts, of which there were ten in each legion: the cohort thus contained 600 men. Among the troops of the second grade (the auxilia) the cohorts were independent foot regiments 500 or 1000 strong, corresponding to the alae, which were similar regiments of cavalry; they were generally posted on the frontiers of the Empire in small forts of four to eight acres, each holding one cohort or ala. The special troops of Rome itself, the Praetorian Guard, the Urbanae Cohortes, and the Vigiles (fire brigade), were divided into cohorts (see further Roman Army). The phrase cohors praetoria or cohors amicorum was sometimes used, especially during the Roman republic, to denote the suite of the governor of a province; hence developed the Praetorian cohorts which formed the emperor’s bodyguard.
In biology, “cohort” is a term for a group of allied orders or families of plants or animals.
COIF (from Fr. coiffe, Ital. cuffia, a cap), a close-fitting covering for the head. Originally it was the name given to a head-covering worn in the middle ages, tied like a night-cap under the chin, and worn out of doors by both sexes; this was later worn by men as a kind of night-cap or skull-cap. The coif was also a close-fitting cap of white lawn or silk, worn by English serjeants-at-law as a distinguishing mark of their profession. It became the fashion to wear on the top of the white coif a small skull-cap of black silk or velvet; and on the introduction of wigs at the end of the 17th century a round space was left on the top of the wig for the display of the coif, which was afterwards covered by a small patch of black silk edged with white (see A. Pulling, Order of the Coif, 1897). The random conjecture of Sir H. Spelman (Glossarium archaiologicum) that the coif was originally designed to conceal the ecclesiastical tonsure has unfortunately been quoted by annotators of Blackstone’s Commentaries as well as by Lord Campbell in his Lives of the Chief Justices. It may be classed with the curious conceit, recorded in Brand’s Popular Antiquities, that the coif was derived from the child’s caul, and was worn on the advocate’s head for luck.
COIMBATORE, a city and district of British India, in the Madras presidency. The city is situated on the left bank of the Noyil river, 305 m. from Madras by the Madras railway. In 1901 it had a population of 53,080, showing an increase of 14% in the decade. The city stands 1437 ft. above sea-level, is well laid out and healthy, and is rendered additionally attractive to European residents by its picturesque position on the slopes of the Nilgiri hills. It is an important industrial centre, carrying on cotton weaving and spinning, tanning, distilling, and the manufacture of coffee, sugar, manure and saltpetre. It has two second-grade colleges, a college of agriculture, and a school of forestry.
The District of Coimbatore has an area of 7860 sq. m. It may be described as a flat, open country, hemmed in by mountains on the north, west and south, but opening eastwards on to the great plain of the Carnatic; the average height of the plain above sea-level is about 900 ft. The principal mountains are the Anamalai Hills, in the south of the district, rising at places to a height of between 8000 and 9000 ft. In the west the Palghat and Vallagiri Hills form a connecting link between the Anamalai range and the Nilgiris, with the exception of a remarkable gap known as the Palghat Pass. This gap, which completely intersects the Ghats, is about 20 m. wide. In the north is a range