The late Mr.John Scott of the Botanic Gardens near Calcutta made many observations for me on worms living under the hot and humid climate of Bengal.The castings abound almost everywhere, in jungles and in the open ground, to a greater degree, as he thinks, than in England.After the water has subsided from the flooded rice-fields, the whole surface very soon becomes studded with castings--a fact which much surprised Mr.Scott, as he did not know how long worms could survive beneath water.They cause much trouble in the Botanic garden, "for some of the finest of our lawns can be kept in anything like order only by being almost daily rolled; if left undisturbed for a few days they become studded with large castings." These closely resemble those described as abounding near Nice; and they are probably the work of a species of Perichaeta.They stand up like towers, with an open passage in the centre.
A figure of one of these castings from a photograph is here given (Fig.3).The largest received by me was 3.5 inches in height and 1.35 inch in diameter; another was only 0.75 inch in diameter and 2.75 in height.In the following year, Mr.Scott measured several of the largest; one was 6 inches in height and nearly 1.5 in diameter: two others were 5 inches in height and respectively 2 and rather more than 2.5 inches in diameter.The average weight of the 22 castings sent to me was 35 grammes (1.25 oz.); and one of them weighed 44.8 grammes (or 2 oz.).All these castings were thrown up either in one night or in two.Where the ground in Bengal is dry, as under large trees, castings of a different kind are found in vast numbers: these consist of little oval or conical bodies, from about the 1/20 to rather above 1/10 of an inch in length.They are obviously voided by a distinct species of worms.
The period during which worms near Calcutta display such extraordinary activity lasts for only a little over two months, namely, during the cool season after the rains.At this time they are generally foundwithin about 10 inches beneath the surface.During the hot season they burrow to a greater depth, and are then found coiled up and apparently hybernating.Mr.Scott has never seen them at a greater depth than 2.5 feet, but has heard of their having been found at 4 feet.Within the forests, fresh castings may be found even during the hot season.The worms in the Botanic garden, during the cool and dry season, draw many leaves and little sticks into the mouths of their burrows, like our English worms; but they rarely act in this manner during the rainy season.
Mr.Scott saw worm-castings on the lofty mountains of Sikkim in North India.In South India Dr.King found in one place, on the plateau of the Nilgiris, at an elevation of 7000 feet, "a good many castings," which are interesting for their great size.The worms which eject them are seen only during the wet season, and are reported to be from 12 to 15 inches in length, and as thick as a man's little finger.These castings were collected by Dr.King after a period of 110 days without any rain; and they must have been ejected either during the north-east or more probably during the previous south-west monsoon; for their surfaces had suffered some disintegration and they were penetrated by many fine roots.A drawing is here given (Fig.4) of one which seems to have best retained its original size and appearance.Notwithstanding some loss from disintegration, five of the largest of these castings (after having been well sun-dried) weighed each on an average 89.5 grammes, or above 3 oz.; and the largest weighed123.14 grammes, or 4.33 oz.,--that is, above a quarter of a pound! The largest convolutions were rather more than one inch in diameter; but it is probable that they had subsided a little whilst soft, and that their diameters had thus been increased.Some had flowed so much that they now consisted of a pile of almost flat confluent cakes.All were formed of fine, rather light-coloured earth, and were surprisingly hard and compact, owing no doubt to the animal matter by which the particles of earth had been cemented together.They did not disintegrate, even when left for some hours in water.Although they had been cast up on the surface of gravelly soil, they contained extremely few bits of rock, the largest of which was only 0.15 inch in diameter.
Dr.King saw in Ceylon a worm about 2 feet in length and 0.5 inch indiameter; and he was told that it was a very common species during the wet season.These worms must throw up castings at least as large as those on the Nilgiri Mountains; but Dr.King saw none during his short visit to Ceylon.
Sufficient facts have now been given, showing that worms do much work in bringing up fine earth to the surface in most or all parts of the world, and under the most different climates.