573 
THE TROPICAL 
AGRICULTURIST. [January 2, 1882. 
of some intelligence. They always plug the entrance, 
sometimes with leaves and sometimes with small stones. 
This may be as a protection from tkeir great enemy, 
th? scolopender, but it is more likely for the sake 
of warmth ; as Mr. Darwin noticed that when kept 
in a room with a fire the performed the work " in 
a slovenly manner." They also often coat, the upper 
part of their burrows with leaves, to prevent their 
bodies from coming into contact with the cold ground. 
Besides eating vegetable and animal food, worms seem 
to some extent to swallow earth for the sake of the 
organic matter it contains ; and their castings are 
composed of such earth, as well as of that which 
has been voided for the excavation of their homes. 
Even in England these castings often attain a con- 
siderable size, but in India and Ceylon they some- 
times reach a height of six inches and weigh as much 
as a quarter of a pound. 
Passing on to his more special subject, Mr. Darwin 
shows l hat the amount of mould thus brought up 
t > the surface by worms may be measured in two 
ways, both of which he followed. The first method 
is by ascertaining the rate at which objects left 
upon the ground are buried : the second and more 
accurate method is by weighing the quantity brought 
up within a given time on a given space. At Maer 
Hall, in Staffordshire, quicklime was spread upon a 
meadow, which was not disturbed for ten years. At 
the end of that time square holes were dug in the field, 
and a lime was found in a layer at a depth of three 
inches from the surface, covered by dark-coloured, fine 
mould, and underlaid by a coarse gravelly or sandy soil. 
In many oilier instances similar results were obtained 
with cinders or marl on chalky or peaty ground. A field 
at Down was so thickly covered with flints that it used 
to be called "the Btoivy field ; " and Mr. Darwin re- 
members doubting whether he would live to see them 
buried in vegetable mould and turf ; but thirty years 
after the worms had worked so vigorously that a horse 
could gallop from one end to the other over compact 
sward, without ever striking a stone. _ A path on the 
lawn at the same place was paved with small flags, 
set edgewise, through which the worms threw up cast- 
ings ; for a while it was swept and weeded, but at 
last it was left alone ; and after several years the 
flags were found buried beneath an inch thickness 
of fine mould. In the same way worms slowly bury 
even big stones ; for when such a stone is left on 
the surface it rests at first, of course on its more 
protubarant parts ; but worms soon fill up with their 
castings Lhe hollows on the lower side, for they like 
the shelter of stones. When the hollows are filled, 
they eject their castings beside the stone ; and as 
the empty burrows collapse the stone slowly sinks. . 
Thus b udders are almost alwayB slightly embedded in 
the soil. The fallen monoliths at Stonebenge have in 
this manner been partially buried, as Mr. Darwin 
elaborately proves. But the second method gives even 
more certain results. Mr. Darwin shows (after Hensen, 
that there must be no less than 53,767 worms living 
in a single acre of land ; and in one case the bur- 
rows numbered nine in two square feet. Some barrels 
of bad vinegar (poisonous to worms) being spilt on 
a small piece oc land, the heaps of dead worms 
found piled on the spot were so amazing as to be 
almost incredible. Mr. Darwin collected and weighed 
tde castings thrown up at various timeB in various 
times in various places, and comes to 1 he conclusion 
that they would amount on the average, in many cases, 
10 a uniform layer of mould one-fifth of an inch thick 
every ye.ir. The chief work of worms in the economy 
of nature is thus to sift the fiuer from the coarser 
particles of the soil, to mingle, the whole with vegetable 
debris, to saturate it with their intestinal secretions, 
and so finally to form that upyer layer of rich mould 
which alone man employs in his agricultural operations. 
Finally, Mr. Darwin considers the part played by 
worms in the disintegration of rocks and denudation 
of the land. It is known that the disintegration of 
rocks is largely due to the acid3 in the humus ; and 
Mr. Darwin shows that such acids are apparently 
generated within the bodies of worms. Moreover, the 
constant interchange of particles between top and 
bottom layers effected by worms brings these acids 
to work more often upon the subjacent rock. Again, 
the small stones swallowed to aid trituration in the 
gizzard are themselves slowly ground down, as was 
proved by their rounded edges under a lens, and this 
must produce no incon-iderable amount of line earth, 
when we remember the vast numbers of worms always 
at work. Not only are the castings composed of very 
fine matter, but the Email fragments of brick or pebble 
found among them are well rounded. The castings 
thus turned out on sloping hillsides are washed away 
in part by the rain towards the vallej^s, and finally 
carried by streams and rivers to the sea. So that in 
the end the insignificant little earthworm turns out 
to be a geological agent of vast importance, to whose 
actions the denudation and sculpture of the earth's 
surface are largely due. And if we doubt the pos- 
sibility of so small and humble an animal perform- 
ing such wonders in the history of our planet, Mr. 
Darwin opportunely reminds us that the cor.d-polyps 
of tropical seas have played almost as large a part in 
the ocean as he believes worms are at present playing 
on the dry land. It is of interest in this connection 
to note the fact, unmentinned by Mr. Darwin, that 
the burrows of annelids are among the very earliest 
fossil indications of the presence of life upon the 
earth.— Pall Mall Budget. 
BRAZILIAN PRODUCTIONS. 
It is creditable to Brazil that, in the great struggle 
for supremacy in the consuming markets of the world, 
no effort is being spared to maintain it by improv- 
ing the quality of coffee and sugar, her chief articles 
of export, the coffee exhibition about to be held in 
Rio de Janeiro being with a view to this laudable 
object. It would appear that Brazilian coffee has been 
made a kind of stalking horse for inferior qualities 
of coffee to ride upon, and tbe result of the exhibition 
must show how far this statement is correct. The 
question is of importance to Brazil and the result will 
be watched with much interest. The large and increas- 
ing production has brought down the price of coffee 
to a very low ebb, from which it does not appear 
likely to rise for some time to come, the speculative 
movement, which so long kept prices at a fictitious 
value in the States, and in some European markets, 
having entirely collapsed. 
The next great staple of sugar is improving in quality 
by the assistance of great central factories in the pro- 
vinces, to which the canea can be sent for grinding, 
with all the appliances of modern machinery, and it 
would appear that this facility is being largely availed 
of by small farmers, who are without adequate means 
of dealing with their canes. We lately published a 
statement from the "Times' as to the larg 3 produc- 
tion of crystalised sugar in Demerara, calling the at- 
tention of Brazilian sugar growers to this improved 
system, by which we hoped they might profit. Both 
the articles of coffee and sugar are capable of being 
rendered more useful to consumers by a careful mani- 
pulation of them in the process of manufacture, and 
it is satisfactory to notice that the Govern: lent is fully 
alive to this necessity. We hear of a Brazdian capit- 
alist who has subscribed 100,000 francs towards the 
establishment of a grand cafe in Paris, where Brazil- 
ian coffee will have fair play, and we heartily wish 
it success. By recent advices from Rio, the crop is 
