Uequhart. — On the Habits of Earth-Worms in Neiv Zealand. 271 



coarser layer, which adhered to the sub-soil. A long strip was left intact, 

 and is being preserved for future observations. Similar layers, which con- 

 sist chiefly of the charred wood, are to be met with in patches, at the same 

 average depth, over several acres of ground. 



The section at the present time shows an even depth of 5f to 6 inches 

 of black mould. The charred wood, especially where holes have been dug, 

 has decayed considerably the last twelve months, reducing the average width 

 to nearly -J an inch, but the layer remains horizontal and parallel to the 

 surface, showing that the worms are evenly distributed, and doing an equal 

 amount of work. The regular way in which the embedded objects sink, in- 

 dependently of their specific gravity, as Mr. Darwin points out, " are the 

 striking features of the case." Pieces of burnt clay If inches in length, 

 weighing over an ounce, small pebbles of jasper rock, fragments of pumice, 

 and the charred wood, have all sunk to the same depth, within the same 

 time, retaining an even thickness that would hardly be expected ; the 

 regular depth of the mould, of course, is partially caused by the levelling 

 action of rain. 



From this it appears that our earth-worms work with the same regu- 

 larity as the British species, and eject — their greater number considered — 

 an equal amount of earth. An addition of about 1 J inches to the superfi- 

 cial surface in eight years, compares favourably with the average cases 

 recorded by Mr. Darwin. Of course the more rapid accumulation of mould 

 the last few years, is owing to the great increase of worms — consequently 

 of worm-castings; although in uncleared lands of this description ' the 

 annual contribution of decayed vegetable matter is in excess of grass-land, 

 its effect in increasing the thickness of the mould is not equal to the work 

 of the greater number of worms. As the flat is cut off from the higher 

 land by a drain, there is no sedimentary deposit ; and the dust blown from 

 desiccated ground is so trifling, that the present increase of mould may be 

 entirely attributed to the work of worms. 



It is probable that when a sufficient depth of vegetable — or perhaps 

 more correctly animal — mould is formed for the worms to live in, that the 

 annual increase of thickness decreases ; for, as a rule, under those circum- 

 stances worms do not penetrate the subsoil to any depth, except when 

 driven down by dry weather. However, in the present case they burrow 

 into the subsoil to a greater depth than worms generally do in the winter 

 months ; as it is of a loose nature it probably contains nutritious matter. 



It may be worth recording that in May, 1876, 1 placed an angular block 

 of trachyte — measuring 9 inches in length, 8 in breadth, and 5f in thick- 

 ness — on the same ground ; in about four years it had sunk nearly 1 inch ; 

 the next two years, it was in the possession of a colony of ants, who no 



