D. S. (David Samuel) Margoliouth.

The Popular science monthly (Volume 19) online

. (page 104 of 110)
Online LibraryD. S. (David Samuel) MargoliouthThe Popular science monthly (Volume 19) → online text (page 104 of 110)
Font size
QR-code for this ebook

McCook went to Texas for the express purpose of studying these ants
in a scientific manner, and as the numerous other observations which
he made, both on these and on the mound-building species, entitle him
to respect, I have not felt justified in suppressing this statement.

The observation made by Colonel Sykes on certain ants in India
has gained a wide notoriety from its having been published by Spence
in his popular work on instinct. Colonel Sykes was a good observer,
so tliat his account ought not to be questioned. He says that in order
to guard his provisions from the ants he put them on a table, the four
legs of which he placed in as many basins filled with water. Some
ants still succeeded in scrambling across the water, and so the legs of
the table were likewise painted with turpentine. The ants then ran
up a wall near which the table stood, and when about a foot above its
level, they sprang from the wall to the table.

Somewhat analogous to this is the observation of Professor Lcuck-
hart, who placed round the trunk of a tree, which had been visited by
ants as a pasture for aphides, a broad cloth soaked in tobacco-water.
When the ants, returning home down the trunk of the tree, arrived at
the soaked cloth, they turned round, went up the tree again to some
of the overhanging branches, and allowed themselves to drop clear of
the obnoxious barrier. On the other hand, the ants which desired to
mount the tree first examined the nature of the obstruction, then
turned back and procured some pellets of earth, which they carried in
their jaws and deposited, one after another, upon the cloth till a harm-
less road of earth was made across it.

This observation of Professor Leuckhart is in turn a corroboration
of an almost identical one made more than a century ago by Cardinal
Fleury, and communicated by him to Reaumur, who published it in
his "Natural History of Insects" (1734). The Cardinal smeared the
trunk of a tree with bird-lime, in order to prevent the ants from
ascending it ; but the insects overcame the obstacle by making a road
of earth, small stones, etc., as in the case just mentioned. On another
occasion the Cardinal saw a number of ants make a bridge across a
vessel of water surrounding the bottom of an orange-tree tub. They
did so by conveying a number of little pieces of xcood, the choice of
that material, instead of earth or stones, as in the previous case, ap-
parently betokening no small knowledge of practical engineering —
a knowledge which, as we shall presently see, is also shared by the


Bttchner, in his recently i^ublished and translated work on " Mind
in Animals," gives a singular observation analogous to the above,
which was communicated to him by Herr G. Theuerkauf. A maple-
tree standing in the grounds of Herr Vollbaum, of Elbing, swarmed
with ants and aphides. In order to check the mischief, the proprietor
smeared about a foot width of the ground around the tree with tar.
The first ants that arrived stuck fast ; but the next, seeing the pre-
dicament of their companions, turned back and fetched a number of
aphides from the tree, which they stuck down on the tar one after
another till they had made a bridge over which they could cross with-
out danger.

It will be observed that all these cases, being so analogous although
recorded independently by different observers, serve to corroborate
one another. As such corroboration in matters of this kind is of
value, I shall here add two or three cases which go to confirm the
observation of Cardinal Fleury regarding the construction of a float-
ing bridge. Dr. Ellendorf writes to Professor BUchner that he pro-
tected a cupboard of his provisions from the invasion of ants by
standing the legs of the cupboard in saucers filled with water. He
adds :

I myself did this, but I none the less found thousands of ants in the cupboard
next morning. It was a puzzle to me how they crossed the water, but the puzzle
was soon solved. For I found a straw in one of the saucers. . . . This they had
used as a bridge. ... I pushed the straw about an inch from the cupboard-leg,
when a terrible coufusion arose. In a moment the leg immediately over the
water was covered with hundreds of ants feeling for the bridge in every direc-
tion with their antennaj, running back again and coming in ever larger swarms,
as though they had communicated to their companions within tlie cupboard the
fearful misfortune that had taken place. Meanwhile the new-comers continued
to run along tlie straw, and, not finding the leg of the cupboard, the greatest per-
plexity arose. They hurried along the edge of the saucer, and soon found where
the fault lay. With united forces they pulled and pushed at the straw, until it
again came into contact with the wood, and the communication was again

The military ants, both in America and Africa, exhibit still more
extraordinary resources in the way of bridge-making. Thus Belt says
of the Ecitons :

I once S2W a wide column trying to pass along a crumbling, nearly perpen-
dicular, slope. They would have got very slowly over it, and many of them
would have fallen ; but a number having secured their bold, and reaching to
each other, remained stationary, and over them the main column passed. An-
other time they were crossing a water-course along a small branch, not thicker
than a goose-quill. They widened this natural bridge to three times its width
by a number of ants clinging to it and to each other on each side, over which
the column passed three or four deep ; whereas, excepting for this expedient,
they would have had to pass over in single file, and treble the time would have
been consumed.


It is remarkable that the military or driving ants of Africa exhibit
precisely similar devices for the bridging of streams as the Ecitons of
America, namely, by forming a chain of individuals over which the
others pass. By means of similar chains they also let themselves
down from trees.

But of the Ecitons another and more recent observer gives an
account of a yet more remarkable device, although no doubt a de-
velopment of the one just described. This obsen'er is Herr H. Krep-
lin, who lived for nearly twenty years in South America as an engineer,
and often had the opportunity of watching the Ecitons. He writes to
Biichner under date 1876 as follows :

If the water-course be narrow, the thick-heads (officers) soon find trees, the
branches of which meet on the bank of either side, and after a short halt the
columns set themselves in motion over these bridges, rearranging themselves in
a narrow train with marvelous quickness on reaching the farther side. But, if
no natural bridge be available for the passage, they travel along the bank of
the river until they arrive at a flat, sandy shore. Each ant now seizes a bit of
dry wood, pulls it into the water and mounts thereon. The hinder rows pusli
the front ones ever farther out, holding on to the wood with their feet and to
their comrades with their jaws. In a short time the water is covered with
ants, and when the raft has grown too large to be held together by the small
creatures' strength, a part breaks otf and begins the journey across, while the
ants left on the bank busily pull their bits of wood into the water and work at
enlarging the ferry-boat until it again breaks. This is repeated as long as an ant
remains on shore.

I shall now bring these numerous instances to a close with a quota-
tion from Belt, which reveals in a most unequivocal manner astonish-
ing powers of observation and reason in the leaf -cutting ants of South
America, the general habits of which we have already considered :

A nest was made near one of our tramways, and to get to the trees the ants
had to cross the rails, over which the wjigons were continually passing and re-
passing. Every time they came along a number of ants were crushed to death.
They persevered in crossing for some time, but at la*t set to work and tunneled
underneath each rail. One day, when the wagons were not running, I stopped
up the tunnels with stones ; but although great numbers carrying leaves were
thus cut off from the nest, they would not cross the rails, but set to work inik-
ing fresh tunnels beneath them.

Such, then, are some of the more well-established facts regarding
the intelligence of ants, and taken altogether they certainly seem to
justify the remark of the most illustrious of naturalists, "The brain
of an ant is one of the most marvelous atoms of matter in the world,
perhaps more so than the brain of a man." — Nineteenth Centunj.




WHATEVER differences of opinion may exist resjiecting the
meteorological influence of forests, it is generally agreed that
in mountainous countries they play an important part in regulating
watei'-courses and in preserving the soil on the slopes of the hills.
This function, which has been observed for a long time, was presented
in a clear light by M. Surrell, engineer of bridges and highways,
whose fine work on the torrents of the high Alps (" Torrens des
Hautes-Alps "), published in 1841, has been the point of departure for
all studies and all legal projects respecting rewooding. While the au-
thor had in view only the restoration of the French Alps, his conclu-
sions are applicable, although in different degrees, to all mountainous
countries ; but the phenomena which he considers are manifested with
the most intensity in the Alps, and the renewal of the woods there is
imposed as a real measure of public policy.

In respect to vegetation, nature has divided the Alpestrian moun-
tains into three zones : creating on the summits, around the rocks and
glaciers, pasture-lands ; on the middle slopes, forests ; in the lower
valleys, lands suited to occupation by agriculture and by villages.
Unfortunately, this natural division has been too often disturbed ; the
inhabitants, leaving the valleys, have established themselves in the
higher regions, have cut down the forests around their houses, and
devoted to cultivation lands which, disintegrated by the plow, are in-
cessantly cut up into ravines by every rain ; or the zone of pasture-
lands has encroached on that of the forests, and has been increased by
the daily devastations of the shepherds. Extending its borders every
year lower down the mountain, it has finished by taking possession of
the slopes and despoiling them of their wood. Gradually the grass
itself, no longer protected by the cover of large trees and continually
fed upon by hungry flocks, has disappeared, leaving behind it only
the denuded flank of the mountain, an easy prey of which the torrents
have not been slow to take possession.

The mountain-torrent is not an ordinary brook, but is a stream with
characters of its own and peculiar ways. Originating in a narrow ba-
sin, the bed of which is very steep, it is subject to sudden variations ;

* [Some instructive reports have recently been published in France concerning the
progress that has been made in rewooding the slopes of the Alps, which, having been
stripped of trees, are most exposed to the ravages of torrents. While the Alps present
features which have no counterpart in the settled regions in the United States, the prob-
lems whieli had to be solved in reclothing tlie lower parts of the mountains with wood
and staying the processes of devastation involve principles which may be applied as well
in our own hilly and mountainous districts. — Editor.]


often wliolly dry, it becomes a flood af^er a storm, and overcomes all
the obstacles that oppose its course. There are clear torrents and
muddy torrents. The former, which are the torrents of eruptive
regions, carry but little matter with them, and are characterized by
sudden freshets, which are due to the fact that the waters running over
impermeable rocks, are precipitated immediately into the ravines and
collect in considerable masses. The torrents of the second class have
formed themselves beds in the loose soil, are continually washing away
the bases of their banks, provoking slides, carrying with them solid
matters derived from the degradation of the hills, and discharging
them in the lower valleys and covering the fields with a thick mud.
The bed of the torrent is washed out more and more, and the banks
increase at the same time ; new ravines are formed, and branches of
them, thus eating away the spur of the mountain, which is gradually
destroyed, or which, undermined at the base, occasionally slides bodily
into the valley, which it closes up.

Attention has long been given to devising means to limit the
ravages of these torrents, which ruin the land, threaten estates, de-
stroy roads, and sometimes even compromise the existence of villages.
Walls have been built along the banks to protect them, or across
the streams to allay the force of the waters. The most efficacious
means, however, as yet discovered, has been to maintain the woods on
the slopes of the mountain. The effect of cutting away the trees in
promoting the formation of torrents has not been doubted by the in-
habitants of mountainous regions, and is clearly set forth by M. Sur-
roll, who says : " When we examine the tracts in the midst of which
torrents of recent origin have been formed, we perceive that they
have in all cases been despoiled of their trees and bushes. If, on the
other hand, we examine hills whose sides have been recently stripped
of wood, we observe that they are cut up by numerous torrents, which
have evidently been formed very lately. Here is a remarkable double
fact: wherever there are recent torrents there, are no longer forests,
and wherever the ground is cleared these torrents are formed ; and
the same eyes that see the woods fall on the declivity of a mountain,
may see appear there immediately a multitude of torrents."

The disastrous consequences of removing the woods from the Alps
began to attract attention in the last century, and have since been dis-
cussed in many publications and official reports. In 1853 the prefect
of the department of the Lower Alps said in a report to the Minister :
" If prompt and energetic measures are not taken, it will be almost
possible to designate the precise moment when the French Alps will
become a desert. The period from 1851 to 1853 will produce a new
diminution in the number of the population. In 1862 the Minister
will remark a continuous and progressive reduction in the number of
hectares devoted to agriculture ; each year will aggravate the evil,
and in a half-century Franco will cDinit more ruins and one depart-


ment less." The departments of the Upper and Lower Alps actually
lost thirty thousand inhabitants, or one ninth of their population, be-
tween 1851 and 1876. A law for recovering the mountains with wood,
which had been prepared by M. For9ade de Rouguet, director-general
of the administration of the forests, was adopted by the legislative
bodies in 1860, and was put in operation shortly afterward.

In some cases, the work of planting woods is left optional, but is
encouraged by the offer of rewards to the communes or individuals
who undertake it. In other cases, where the public interest is at stake,
the state determines the area of land to be planted, and allows the pro-
prietors to perform the work if they will ; if they refuse to do so, it
attends to the matter itself, taking care that its proceedings shall be
as inoffensive to the people as they can be made, and be at the same
time effective.

The first question that is presented in dealing with a hill that has
been cut up with ravines is to determine the perimeter of the lands to
be restored. The area should not be limited to the banks of the tor-
rent and its branches, for these banks, being continually undermined
and always changing, would continue, by giving way, to enlarge the
basin if they were not themselves fixed by vegetation. The justice of
the rules which M. Surrell laid down on this point in 1841 has been
confirmed by experience. We should begin, he said, to trace along
either bank of the torrent a continuous line which shall pursue all the
inflections of its course, from its remote origin till it issues from the
gorge upon the lower valley. The tract included between each of
these lines and the crest of the banks would form what I would call a
zone of defense. The zones of the two banks would meet at the upper
end, following the contour of the basin, and would thus surround the
torrent, like a belt, in its whole extent. Their width, which should
vary with the degree of the slope and the consistency of the soil, may
be as little as fifty yards at the lower end, but should increase rapidly
as the zone rises up the mountain, and should end by including spaces
of five or six hundred yards. This delineation is applicable not only
to the principal branch of the torrent, but also to the secondary tor-
rents that empty into it, and to the smaller ravines departing from
each of these torrents, and thus, pursuing one branch after another,
should not stop till it reaches the source of the most remote rill. As
these zones of defense go on enlarging up the mountain, they will join,
and even merge into each other toward the summit, so as to form a
continuous band around the upper part, leaving no void in it.

The perimeter of the land to be rewooded having been determined,
the next step is to prohibit pasturage, in order to prevent further dis-
integration of the soil by the feet of the sheep, and allow the grass to
recover. The ultimate result is assisted by cutting the bushes down
to the stump, and planting willow-cuttings in horizontal rows about
two yards apart, to hold the earth on the almost vertical slopes, and


then sowing the seeds of grasses in the intervals. Concurrently with
these preliminary operations, the only object of which is to prepare
the soil for the reception of the forest-growth to be planted later,
the torrent itself is attacked with works intended to impede its course,
hold back the drift-matter, and prevent further undermining of the
banks. For this purpose wattles and bars are inserted along the
stream and its smallest ramifications, beginning generally at the upper
parts, where the water, not having acquired its full force, can be more
easily stopped, and the suspended matter may be more easily retained.
Green branches of willow and hazel are woven around stakes in the
ravine, take root in the soil, and become a living obstacle which per-
petuates itself. If the wattles are close enough together, they will
transform the ravine into a kind of staircase, by the agency of which
the violence of the water is allayed at each step, its force is lessened so
tliat it does not wear upon the soil, and it is made to run almost clear.

More energetic measures are required lower down, where the tor-
rent exercises a more destructive action. Here dams of masonry are
inserted in the banks, provided with an arched channel in the lower
part to permit the outflow of water at moderate stages of the stream ;
they serve to hold back the stones that are worked out from the moun-
tain, to promote the growth of alluvions, to break the fall of the tor-
rent and diminish its violence by enlarging its bed. Some of these
dams are real works of constructive art, and have cost as much as
eight or ten thousand dollars.

The real replanting of the woods is done after the ground has be-
come settled and the torrent has been subdued. Nurseries of young
trees suitable for the purpose are previously established near the local-
ity of the works, which are drawn upon as the plants are needqd. The
species vary according to the nature of the situation and the soil.
Generally pines and firs of diflFerent kinds are best adapted to the
higher situations, deciduous trees to the lower ones. Use has also
been made of several species of shrubs and bushes, which with their
branching roots are wonderfully fitted to fix the earth, and by rea-
son of their rapid growth quickly furnish a shade to the bare sur-
face. The planting is begun at the top of the elevation and is con-
ducted downward, in such a manner as to leave no places vacant. The
young trees, protected against the sun by the grasses which were
previously sown and by the willow-cuttings which have already taken
root, soon begin to grow with vigor. An effort was made, in accord-
ance with the law of 1864, to substitute regrassing for replanting with
wood in the interior of the perimeters ; but it did not answer the pur-
pose of consolidating the soil, and was abandoned. Sometimes the
communes have shown themselves hostile to the execution of these
works on account of the interdiction of pasturage. Such was the
case in the communes of Orres and Saint-Sauveur, whose inhabitants
drove away the workmen in 1804. The work was resumed three

TOL. XIX. — 53


years afterward, after it had been completed in an adjoining commune,
and the people were conciliated by being employed in it. The upper
valley of the torrent of Vacheres, which was formerly considered one
of the largest and most violent torrents of the Alps, once all cut up
into ravines, is now covered with vegetation, and the torrent itself is
described as extinct ; once the terror of the country, it has been
changed, at an expense of twenty-four thousand dollars, into an inof-
fensive river.

Like results have been obtained wherever works of the kind have
been executed. M, Gentil, an engineer, reports of one district : " The
aspect of the mountain has been changed all at once. The soil has
acquu-ed such stability that the violent storms of 1868, which caused
great disasters in the high Alps, fell harmlessly on the regenerated
perimeters. The mountain has at the same time become productive ;
where a few sheep could hardly live by destroying everything, mty
now be seen abundance of grass fit to mow. This method of improve-
ment is remarkable for giving the people what they need most, and
for giving it to them with only a brief delay. The pastoral inhabi-
tants find food for their flocks in the grasses and hay of the planted
areas and in the foliage of the trees ; and the acacias that have been
caused to grow there wull soon furnish them the wood they will need
in their vineyards. The torrential character of the stream has disap-
peared ; the water is less turbid, even in time of rain, and is better
adapted to purposes of irrigation. It is no longer loaded with solid
matter when it reaches the lower valleys, and naturally keeps its bed.
. . . Diversions from the regular course are less liable to occur and
less dangerous, and the people on its banks can prote>ct themselves
"with slight expense." M. Gentil relates several examples of torrents
formerly very dangerous which have been fully and permanently sub-
dued by means of such works as have been here described, giving pro-
tection to highways that were often interrupted before, and security
to valleys that were often in danger, and adds : " Immense benefits
have accrued to the lands situated in the lower valleys near the dis-
charging basins of the streams. Not only are the inhabitants delivered
from the expense of keeping up costly and precarious dikes ; their
property, also, being no longer in danger of being suddenly buried
under a flood of gravel, has acquired a fixed value. They are able to
till their land hopefully, and with the assurance that they will enjoy
the crop. This certainty is a blessing of enormous value. The pro-
prietor, able to rely upon the future, will no longer think of leaving
the country."

So far as the work of restoration has been executed, its success —
in respect to the processes employed and the results obtained — has
been complete. The chief question concerning it which remains is as
to the extent to which it shall be systematically carried out. — Bemu
des Deux Mondes.



pkofessok tn the polytecnnic school of rio janeiro.*

CATTLE-RAISIXG is far from having attained a sufficient im-
portance in Brazil. Immense provinces, like those of Goyaz
and Matto-Grosso, vast regions from the Amazon to the Parana, where
cattle could be raised easily and without care, remain unutilized for
want of a market and of convenient means of transport and conserva-
tion. There exist, however, some important stock-raising tracts and

Online LibraryD. S. (David Samuel) MargoliouthThe Popular science monthly (Volume 19) → online text (page 104 of 110)