IN'DUS (Lat., from Ok.'Iv(501, from Skt. ,Sind ha, river). The great river that bounds India on the west. separating it from Afghanistan and Baluchistan (Slap: India, A 3). It is over 1800 miles long, and the drainage area of its basin is estimated at 372.000 square miles. It rises 50 miles southeast of Gartok, an impor tant trading centre in Tibet. its source being 15, 000 feet above the level of the sea, on the north side of Kailas, a Himalayan peak, 22,on0 feet high. Its general course, till it forces its way between tho Himalaya proper and the Hindu Kush, is toward the northwest. It flows past Leh, the capital of Ladak; receives the waters of its important Trans-Himalayan tributary, the Shyok, from the north; and after a descent of 11,000 feet in a course of 500 miles, through some of the grandest mountain scenery of the world, about GO miles below Iskardo bends sharply southward, above the confluence of the Gilgit. It flows past Bunji. on the Kashmir-Kohistan border, and 20 miles below takes a western emirs,- to Kotgata, where again it turns south ward. and at Darband emerges from the Kohis tan Mountains into the plains of the Punjab. It becomes navigable at Attock (ancient Taxila), the scene of Alexander the Great's passage., 870 miles from its source. Here it receives the Kabul River (q.v.), its chief affluent on the right. Continuing past Dern Ismail Khan. Dera Ghnzi Khan, and other minor towns, near Ali thankot, about midway in its further course of 940 miles to the Arabian Sea, it receives the waters of the Chenab, the (Mara, the Jhelum, the Ravi, the Bens, and the Sutlej, through the Panjnad (literally 'five rivers,' which gives its name to the Punjab). Each of these rivers, as well as the Kabul, is practicable for inland craft to the mountains.
Below the confluence of the Panjnad the vol ume of the Indus, past Sakkar and 1Iyderabad, becomes gradually less. Through the arid. rain less, alluvial plain of Sindh it divides into nu merous channels, many of which do not. return to the main stream, while others return much shrunken in volume. This wasting of the waters
is not very apparent to the eye, owing to the gradual slackening of the current and the ascent of the tides. Aliani, S miles north of Ilyiloraliad and 75 miles from the sea, is the head of the delta which extends for 130 miles along the coast of the Arabian Sea. The chief outlets of the Indus are the .11;t1, and Vatho mouths. The annual rise of the river, owing to the melt ing of the mountain snows, extends from May to August, and is often attended by considerablo inundations and (Images of the deltaic channels, chiefly owing to t he enormous amount of sand and clayey silt brought down by the current. :Modern engineering has done much to obviate the inconveniences caused. The value of the Indus as a navigable route of traffic, never con siderable, has been lessened since the building of railways through its valley from Karachi to Attock, and navigation is now confined to na tive craft. in a hot climate, where precipita tion is almost nil. the river is more important as a means of irrigation, and the various works toward this end inaugurated by the British Gov ernment have led to a remarkable agricultural development throughout Sindh. The river is spanned by several modern bridges, of which the chief is the lunge cantilever bridge at Sakkar, and the northernmost an iron suspension bridge above Bunji. Fish of excellent quality abound in its waters, and form the staple article of Coln inerre and food of the surrounding country. The gavial, or long-snouted alligator, is the amphibi ous reptile of the river. The Indus is the 'King River' of Vedic poetry.
INDUSrUM, or -zlif-um (Lat., tunic). In ferns, a flap-like outgrowth which covers the sores or group of spore-cases (spo rangial. Indusia are exceedingly varied in structure, an I furnish diameters for classifiea lion. Occasionally the sporangia are developed along the leafy inargin which Unrolls to cover them, as in the maidenhair fern and the eorninon bracken. In this case the in•olled leaf-margin is spoken of as a 'false indusitun.' See FERN.