Chapter 2

HABITS OF WORMS--continued.

Manner in which worms seize objects--Their power of suction--The instinct of plugging up the mouths of their burrows--Stones piled over the burrows--The advantages thus gained--Intelligence shown by worms in their manner of plugging up their burrows--Various kinds of leaves and other objects thus used--Triangles of paper--Summary of reasons for believing that worms exhibit some intelligence--Means by which they excavate their burrows, by pushing away the earth and swallowing it--Earth also swallowed for the nutritious matter which it contains--Depth to which worms burrow, and the construction of their burrows--Burrows lined with castings, and in the upper part with leaves--The lowest part paved with little stones or seeds--Manner in which the castings are ejected--The collapse of old burrows--Distribution of worms--Tower-like castings in Bengal--Gigantic castings on the Nilgiri Mountains--Castings ejected in all countries.

In the pots in which worms were kept, leaves were pinned down to the soil, and at night the manner in which they were seized could be observed. The worms always endeavoured to drag the leaves towards their burrows; and they tore or sucked off small fragments, whenever the leaves were sufficiently tender. They generally seized the thin edge of a leaf with their mouths, between the projecting upper and lower lip; the thick and strong pharynx being at the same time, as Perrier remarks, pushed forward within their bodies, so as to afford a point of resistance for the upper lip. In the case of broad flat objects they acted in a wholly different manner. The pointed anterior extremity of the body, after being brought into contact with an object of this kind, was drawn within the adjoining rings, so that it appeared truncated and became as thick as the rest of the body. This part could then be seen to swell a little; and this, I believe, is due to the pharynx being pushed a little forwards. Then by a slight withdrawal of the pharynx or by its expansion, a vacuum was produced beneath the truncated slimy end of the body whilst in contact with the object; and by this means the two adhered firmly together. {28} That under these circumstances a vacuum was produced was plainly seen on one occasion, when a large worm lying beneath a flaccid cabbage leaf tried to drag it away; for the surface of the leaf directly over the end of the worm's body became deeply pitted. On another occasion a worm suddenly lost its hold on a flat leaf; and the anterior end of the body was momentarily seen to be cup-formed. Worms can attach themselves to an object beneath water in the same manner; and I saw one thus dragging away a submerged slice of an onion-bulb.

The edges of fresh or nearly fresh leaves affixed to the ground were often nibbled by the worms; and sometimes the epidermis and all the parenchyma on one side was gnawed completely away over a considerable space; the epidermis alone on the