Scientific American Supplement, No. 446, July 19, 1884 by Various
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Various >> Scientific American Supplement, No. 446, July 19, 1884
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At that time of the year the stream was receding, and the meadow was
beginning to dry. At a period not over a month previous, the meadows, at
least as far from the stream as the burrows were found, had been covered
with water. Those burrows near the stream were less than six inches
deep, and there was a gradual increase in depth as the distance from the
stream became greater. Moreover, the holes farthest from the stream were
in nearly every case covered by a mound, while those nearer had either a
very small chimney or none at all, and subsequent visits proved that at
that time of year the mounds were just being constructed, for each time
I revisited the place the mounds were more numerous.
[Illustration: Fig. 1 Section of Crayfish burrow]
The length, width, general direction of the burrows, and number of the
openings were extremely variable, and the same is true of the mounds.
Fig. 1 illustrates a typical burrow shown in section. Here the main
burrow is very nearly perpendicular, there being but one oblique opening
having a very small mound, and the main mound is somewhat wider than
long. Occasionally the burrows are very tortuous, and there are often
two or three extra openings, each sometimes covered by a mound. There is
every conceivable shape and size in the chimneys, ranging from a mere
ridge of mud, evidently the first foundation, to those with a breadth
one-half the height. The typical mound is one which covers the
perpendicular burrow in Fig. 1, its dimensions being six inches broad
and four high. Two other forms are shown in Fig. 2. The burrows near the
stream were seldom more than six inches deep, being nearly
perpendicular, with an enlargement at the base, and always with at least
one oblique opening. The mounds were usually of yellow clay, although in
one place the ground was of fine gravel, and there the chimneys were of
the same character. They were always circularly pyramidal in shape, the
hole inside being very smooth, but the outside was formed of irregular
nodules of clay hardened in the sun and lying just as they fell when
dropped from the top of the mound. A small quantity of grass and leaves
was mixed through the mound, but this was apparently accidental.
The size of the burrows varied from half an inch to two inches in
diameter, being smooth for the entire distance, and nearly uniform in
width. Where the burrow was far distant from the stream, the upper part
was hard and dry. In the deeper holes I invariably found several
enlargements at various points in the burrow. Some burrows were three
feet deep, indeed they all go down to water, and, as the water in the
ground lowers, the burrow is undoubtedly projected deeper. The diagonal
openings never at that season of the year have perfect chimneys, and
seldom more than a mere rim. In no case did I find any connection
between two different burrows. In digging after the inhabitants I was
seldom able to secure a specimen from the deeper burrows, for I found
that the animal always retreated to the extreme end, and when it could
go no farther would use its claws in defense. Both males and females
have burrows, but they were never found together, each burrow having but
a single individual. There is seldom more than a pint of water in each
hole, and this is muddy and hardly suitable to sustain life.
[Illustration: Fig. 2 Crayfish Mound]
The neighboring brooks and springs were inhabited by another species of
crayfish, _Cambaras bartonii_, but although especial search was made for
the burrowing species, in no case was a single specimen found outside of
the burrows. _C. bartonii_ was taken both in the swiftly running
portions of the stream and in the shallow side pools, as well as in the
springs at the head of small rivers. It would swim about in all
directions, and was often found under stones and in little holes and
crevices, none of which appeared to have been made for the purpose of
retreat, but were accidental. The crayfishes would leave these little
retreats whenever disturbed, and swim away down stream out of sight.
They were often found some distance from the main stream under rocks
that had been covered by the brook at a higher watermark; but although
there was very little water under the rocks, and the stream had not
covered them for at least two weeks, they showed no tendency to burrow.
Nor have I ever found any burrows formed by the river species _Cumbarus
affinis._ although I have searched over miles of marsh land on the
Potomac for this purpose.
[Illustration: Fig. 2 Crayfish Mound (shorter)]
The brook near where my observations were made was fast decreasing in
volume, and would probably continue to do so until in July its bed would
be nearly dry. During the wet seasons the meadow is itself covered. Even
in the banks of the stream, then under water, there were holes, but they
all extended obliquely without exception, there being no perpendicular
burrows and no mounds. The holes extended in about six inches, and there
was never a perpendicular branch, nor even an enlargement at the end. I
always found the inhabitant near the mouth, and by quickly cutting off
the rear part of the hole could force him out, but unless forcibly
driven out it would never leave the hole, not even when a stick was
thrust in behind it. It was undoubtedly this species that Dr. Godman
mentioned in his "Rambles of a Naturalist," and which Dr. Abbott _(Am.
Nal.,_ 1873, p. 81) refers to _C. bartonii_. Although I have no proof
that this is so, I am inclined to believe that the burrowing crayfishes
retire to the stream in winter and remain there until early spring, when
they construct their burrows for the purpose of rearing their young and
escaping the summer droughts. My reason for saying this is that I found
one burrow which on my first visit was but six inches deep, and later
had been projected to a depth at least twice as great, and the
inhabitant was an old female.
I think that after the winter has passed, and while the marsh is still
covered with water, impregnation takes place and burrows are immediately
begun. I do not believe that the same burrow is occupied for more than
one year, as it would probably fill up during the winter. At first it
burrows diagonally, and as long as the mouth is covered with water is
satisfied with this oblique hole. When the water recedes, leaving the
opening uncovered, the burrow must be dug deeper, and the economy of a
perpendicular burrow must immediately suggest itself. From that time the
perpendicular direction is preserved with more or less regularity.
Immediately after the perpendicular hole is begun, a shorter opening to
the surface is needed for conveying the mud from the nest, and then the
perpendicular opening is made. Mud from this, and also from the first
part of the perpendicular burrow, is carried out of the diagonal opening
and deposited on the edge. If a freshet occurs before this rim of mud
has had a chance to harden, it is washed away, and no mound is formed
over the oblique burrow.
After the vertical opening is made, as the hole is bored deeper, mud is
deposited on the edge, and the deeper it is dug the higher the mound. I
do not think that the chimney is a necessary part of the nest, but
simply the result of digging. I carried away several mounds, and in a
week revisited the place, and no attempt had been made to replace them;
but in one case, where I had in addition partly destroyed the burrow by
dropping mud into it, there was a simple half rim of mud around the
edge, showing that the crayfish had been at work; and as the mud was dry
the clearing must have been done soon after my departure. That the
crayfish retreats as the water in the ground falls lower and lower is
proved by the fact that at various intervals there are bottled-shaped
cavities marking the end of the burrow at an earlier period. A few of
those mounds farthest from the stream had their mouths closed by a
pellet of mud. It is said that all are closed during the summer months.
How these animals can live for months in the muddy, impure water is to
me a puzzle. They are very sluggish, possessing none of the quick
motions of their allied _C. bartonii,_ for when taken out and placed
either in water or on the ground, they move very slowly. The power of
throwing off their claws when these are grasped is often exercised.
About the middle of May the eggs hatch, and for a time the young cling
to the mother, but I am unable to state how long they remain thus. After
hatching they must grow rapidly, and soon the burrow will be too small
for them to live in, and they must migrate. It would be interesting to
know more about the habits of this peculiar species, about which so
little has been written. An interesting point to settle would be how and
where it gets its food. The burrow contains none, either animal or
vegetable. Food must be procured at night, or when the sun is not
shining brightly. In the spring and fall the green stalks of meadow
grasses would furnish food, but when these become parched and dry they
must either dig after and eat the roots, or search in the stream. I feel
satisfied that they do not tunnel among the roots, for if they did so
these burrows would be frequently met with. Little has as yet been
published upon this subject, and that little covers only two spring
months--April and May--and it would be interesting if those who have an
opportunity to watch the species during other seasons, or who have
observed them at any season of the year, would make known their results.
RALPH S. TARR
* * * * *
OUR SERVANTS, THE MICROBES.
Who of us has not, in a partially darkened room, seen the rays of the
sun, as they entered through apertures or chinks in the shutters,
exhibit their track by lighting up the infinitely small corpuscles
contained in the air? Such corpuscles always exist, except in the
atmosphere of lofty mountains, and they constitute the dust of the air.
A microscopic examination of them is a matter of curiosity. Each flock
is a true museum (Fig. 1), wherein we find grains of mineral substances
associated with organic debris, and germs of living organisms, among
which must be mentioned the _microbes_.
Since the splendid researches of Mr. Pasteur and his pupils on
fermentation and contagious diseases, the question of microbes has
become the order of the day.
In order to show our readers the importance of the study of the
microbes, and the results that may be reached by following the
scientific method created by Mr. Pasteur, it appears to us indispensable
to give a summary of the history of these organisms. In the first place,
what is a microbe? Although much employed, the word has not been well
defined, and it would be easy to find several definitions of it. In its
most general sense, the term microbe designates certain colorless algae
belonging to the family Bacteriaceae, the principal forms of which are
known under the name of _Micrococcus. Bacterium, Bacillus. Vibrio,
/Spirillum, etc_.
In order to observe these different forms of Bacteriaceae it is only
necessary to examine microscopically a drop of water in which organic
matter has been macerated, when there will be seen _Micrococci_ (Fig. 2,
I.)looking like spherical granules, _Bacteria_ in the form of very short
rods, _Bacilli_ (Fig. 2, V.), _Vibriones_ (Fig. 2, IV.,) moving their
straight or curved filaments, and _Spirilli_ (Fig. 2, VI.), rolled up
spirally. These varied forms are not absolutely constant, for it often
happens in the course of its existence that a species assumes different
shapes, so that it is difficult to take the form of these algae as a
basis for classifying them, when all the phases of their development
have not been studied.
The Bacteriaceae are reproduced with amazing rapidity. If the temperature
is proper, a limpid liquid such as chicken or veal broth will, in a few
hours, become turbid and contain millions of these organisms.
Multiplication is effected through fission, that is to say, each globule
or filament, after elongating, divides into two segments, each of which
increases in its turn, to again divide into two parts, and so on (Fig.
2, I. b). But multiplication in this way only takes place when the
bacteria are placed in a proper nutritive liquid; and it ceases when the
liquid becomes impoverished and the conditions of life become difficult.
It is at this moment that the formation of _spores_ occurs--reproductive
bodies that are destined to permit the algae to traverse, without
perishing, those phases where life is impossible. The spores are small,
brilliant bodies that form in the center or at the extremity of each
articulation or globule of the bacterium (Fig. 2, II. l), and are set
free through the breaking up of the joints. There are, therefore, two
phases to be distinguished in the life of microbes--that of active life,
during which they multiply with great rapidity, are most active, and
cause sicknesses or fermentations, and that of retarded life, that is to
say, the state, of resting spores in which the organisms are inactive
and consequently harmless. It is curious to find that the resistance to
the two causes of destruction is very different in the two cases.
In the state of active life the bacterides are killed by a temperature
of from 70 to 80 degrees, while the spores require the application of a
temperature of from 100 to 120 degrees to kill them. Oxygen of a high
pressure, which is, as well known from Bert's researches, a poison for
living beings, kills many bacteria in the state of active life, but has
no influence upon their spores.
In a state of active life the bacteriae are interesting to study. The
absence of green matter prevents them from feeding upon mineral matter,
and they are therefore obliged to subsist upon organic matter, just as
do plants that are destitute of chlorophyl (such as fungi, broomrapes,
etc.). This is why they are only met with in living beings or upon
organic substances. The majority of these algae develop very well in the
air, and then consume oxygen and exhale carbonic acid, like all living
beings. If the supply of air be cut off, they resist asphyxia and take
the oxygen that they require from the compounds that surround them. The
result is a complete and rapid decomposition of the organic materials,
or a fermentation. Finally, there are even certain species that die in
the presence of free oxygen, and that can only live by protecting
themselves from contact with this gas through a sort of jelly. These are
ferments, such as _Bacillus amylobacter,_ or butyric ferment, and _B.
septicus_, or ferment of the putrefaction of nitrogenized substances.
[Illustration: FIG. 1.--ATMOSPHERIC DUST.]
These properties explain the regular distribution of bacteria in liquids
exposed to the air. Thus, in water in which plants have been macerated
the surface of the liquid is occupied by _Bacillus subtilis_. which has
need of free oxygen in order to live, while in the bulk of the liquid,
in the vegetable tissues, we find other bacteria, notably _B.
amylobacter_, which lives very well by consuming oxygen in a state of
combination. Bacteria, then, can only live in organic matters, now in
the presence and now in the absence of air.
What we have just said allows us to understand the process of
cultivating these organisms. When it is desired to obtain these algae,
we must take organic matters or infusions of such. These liquids or
substances are heated to at least 120 deg. in order to kill the germs that
they may contain, and this is called "sterilizing." In this sterilized
liquid are then sown the bacteria that it is desired to study, and by
this means they can be obtained in a state of very great purity.
The Bacteriaceae are very numerous. Among them we must distinguish those
that live in inert organic matters, alimentary substances, or debris of
living beings, and which cause chemical decompositions called
fermentations. Such are _Mycoderma aceti_, which converts the alcohol of
fermented beverages into vinegar; _Micrococcus ureae_, which converts
the urea of urine into carbonate of ammonia, and _Micrococcus
nitrificans,_ which converts nitrogenized matters into intrates, etc.
Some, that live upon food products, produce therein special coloring
matters; such are the bacterium of blue milk, and _Micrococcus
prodigiosus_ (Fig. 2, I.), a red alga that lives upon bread and forms
those bloody spots that were formerly considered by the superstitious as
the precursors of great calamities.
[Illustration: Fig. 2.--VARIOUS MICROBES. (Highly magnified.)]
Another group of bacteria has assumed considerable importance in
pathology, and that is the one whose species inhabit the tissues of
living animals, and cause more or less serious alterations therein, and
often death. Most contagious diseases and epidemics are due to algae of
this latter group. To cite only those whose origin is well known, we may
mention the bacterium that causes charbon, the micrococcus of chicken
cholera, and that of hog measles.
It will be seen from this sketch how important the study of these
organisms is to man, since be must defend his body against their
invasions or utilize them for bringing about useful chemical
modifications in organic matters.
_Our Servants._--We scarcely know what services microbes may render us,
yet the study of them, which has but recently been begun, has already
shown, through the remarkable labors of Messrs. Pasteur, Schloesing and
Muntz, Van Tieghem, Cohn, Koch, etc., the importance of these organisms
in nature. All of us have seen wine when exposed to air gradually sour,
and become converted into vinegar, and we know that in this case the
surface of the liquid is covered with white pellicles called "mother of
vinegar." These pellicles are made up of myriads of globules of
_Mycoderma aceti_. This mycoderm is the principal agent in the
acidification of wine, and it is it that takes oxygen from the air and
fixes it in the alcohol to convert it into vinegar. If the pellicle that
forms becomes immersed in the liquid, the wine will cease to sour.
The vinegar manufacturers of Orleans did not suspect the role of the
mother of vinegar in the production of this article when they were
employing empirical processes that had been established by practice. The
vats were often infested by small worms ("vinegar eals") which disputed
with the mycoderma for the oxygen, killed it through submersion, and
caused the loss of batches that had been under troublesome preparation
for months. Since Mr. Pasteur's researches, the _Mycoderma aceti_ has
been sown directly in the slightly acidified wine, and an excellent
quality of vinegar has thus been obtained, with no fear of an occurrence
of the disasters that accompanied the old process.
Another example will show us the microbes in activity in the earth. Let
us take a pinch of vegetable mould, water it with ammonia compounds, and
analyze it, and we shall find nitrates therein. Whence came these
nitrates? They came from the oxidation of the ammonia compounds brought
about by moistening, since the nitrogen of the air does not seem to
combine under normal conditions with the surrounding oxygen. This
oxidation of ammonia compounds is brought about, as has been shown by
Messrs. Schloesing and Muntz, by a special ferment, the _Micrococcus
nitrificans_, that belongs to the group of Bacteriacae. In fact, the
vapors of chloroform, which anesthetize plants, also prevent
nitrification, since they anaesthetize the nitric ferment. So, too, when
we heat vegetable humus to 100 deg., nitrification is arrested, because the
ferment is killed. Finally, we may sow the nitric ferment in calcined
earth and cause nitrification to occur therein as surely as we can bring
about a fermentation in wine by sowing _Mycoderma aceti_ in it.
The nitric ferment exists in all soils and in all latitudes, and
converts the ammoniacal matters carried along by the rain into nitrates
of a form most assimilable by plants. It therefore constitutes one of
the important elements for fertilizing the earth.
Finally, we must refer to the numerous bacteria that occasion
putrefaction in vegetable or animal organisms. These microbes, which
float in the air, fall upon dead animals or plants, develop thereon, and
convert into mineral matters the immediate principles of which the
tissues are composed, and thus continually restore to the air and soil
the elements necessary for the formation of new organic substances.
Thus, _Bacillus amylobacter_ (Fig. 2, II.), as Mr. Van Tieghem has
shown, subsists upon the hydrocarbons contained in plants, and
disorganizes vegetable tissues in disengaging hydrogen, carbonic acid,
and vegetable acids. _Bacterium roseopersicina_ forms, in pools, rosy or
red pellicles that cover vegetable debris and disengage gases of an
offensive odor. This bacterium develops in so great quantity upon low
shores covered with fragments of algae as to sometimes spread over an
extent of several kilometers. These microbes, like many others,
continuously mineralize organic substances, and thus exhibit themselves
as the indispensable agents of the movement of the matter that
incessantly circulates from the mineral to the organic world, and _vice
versa_.--_Science et Nature._
* * * * *
Palms sprouted from seeds kept warm by contact of the vessel with the
water boiler of a kitchen range are grown by a man in New York.
* * * * *
EPITAPHIUM CHYMICUM.
The following epitaph was written by a Dr. Godfrey, who died in Dublin
in 1755:
Here lieth, to _digest macerate_, and _amalgamate_ into clay,
_In Batneo Arenae_,
_Stratum super Stratum_
The _Residuum, Terra damnata_ and _Caput Mortuum_,
Of BOYLE GODFREY, Chymist and M.D.
A man who in this Earthly Laboratory pursued various
_Processes_ to obtain _Arcanum Vitae_,
Or the Secret to Live;
Also _Aurum Vitae_,
or the art of getting rather than making gold.
_Alchymist_-like, all his Labour and _Projection_,
as _Mercury_ in the Fire, _Evaporated_ in _Fume_ when he
_Dissolved_ to his first principles.
He _departed_ as poor
as the last drops of an _Alembic_; for Riches are not
poured on the _Adepts_ of this world.
Though fond of News, he carefully avoided the
_Fermentation, Effervescence_, and _Decrepitation_ of this
life. Full seventy years his _Exalted Essence_
was _hermetically_ sealed in its _Terrene Matrass_; but the
Radical Moisture being _exhausted_, the _Elixir Vitae_ spent,
And _exsiccate_ to a _Cuticle_, he could not _suspend_
longer in his _Vehicle_, but _precipitated Gradatim, per_
_Campanam_, to his original dust.
May that light, brighter than _Bolognian Phosphorus_,
Preserve him from the _Athanor, Empyreuma_, and _Reverberatory
Furnace_ of the other world,
Depurate him from the _Faeces_ and _Scoria_ of this,
Highly _Rectify_ and _Volatilize_, his _aethereal_ spirit,
Bring it over the _Helm_ of the _Retort_ of this Globe, place
in a proper _Recipient_ or _Crystalline_ orb,
Among the elect of the _Flowers of Benjamin_; never to
be _saturated_ till the General _Resuscitation, Deflagration,
Calcination,_ and _Sublimation_ of all things.
* * * * *
A NEW STOVE CLIMBER.
(_Ipomaea thomsoniana_.)
The first time we saw flowers of this beautiful new climbing plant
(about a year ago) we thought that it was a white-flowered variety of
the favorite old Ipomaea Horsfalliae, as it so nearly resembles it. It
has, however, been proved to be a distinct new species, and Dr. Masters
has named it in compliment to Mr. Thomson of Edinburgh. It differs from
I. Horsfalliae in having the leaflets in sets of threes instead of fives,
and, moreover, they are quite entire. The flowers, too, are quite double
the size of those of Horsfalliae, but are produced in clusters in much
the same way; they are snow-white. This Ipomaea is indeed a welcome
addition to the list of stove-climbing plants, and will undoubtedly
become as popular as I. Horsfalliae, which may be found in almost every
stove. It is of easy culture and of rapid growth, and it is to be hoped
that it is as continuous in flowering as Horsfalliae. It is among the new
plants of the year now being distributed by Mr. B.S. Williams, of the
Victoria Nurseries, Upper Holloway.--_The Garden_.
[Illustration: A NEW STOVE CLIMBER. IPOMAEA THOMSONIANA.]
* * * * *
HISTORY OF WHEAT.
Isis was supposed to have introduced wheat into Egypt, Demeter into
Greece, and the Emperor Chin-Wong into China, about 3000 B.C. In Europe
it was cultivated before the period of history, as samples have been
recovered from the lacustrine dwellings of Switzerland.
The first wheat raised in the "New World" was sown by the Spaniards on
the island of Isabella, in January, 1494, and on March the 30th the ears
were gathered. The foundation of the wheat harvest of Mexico is said to
have been three or four grains carefully cultivated in 1530, and
preserved by a slave of Cortez. The first crop of Quito was raised by a
Franciscan monk in front of the convent. Garcilasso de la Vega affirms
that in Peru, up to 1658, wheaten bread had not been sold in Cusco.
Wheat was first sown by Goshnold Cuttyhunk, on one of the Elizabeth
Islands in Buzzard's Bay, off Massachusetts, in 1602, when he first
explored the coast. In 1604, on the island of St. Croix, near Calais,
Me., the Sieur de Monts had some wheat sown which flourished finely. In
1611 the first wheat appears to have been sown in Virginia. In 1626,
samples of wheat grown in the Dutch Colony at New Netherlands were shown
in Holland. It is probable that wheat was sown in the Plymouth Colony
prior to 1629, though we find no record of it, and in 1629 wheat was
ordered from England to be used as seed. In 1718 wheat was introduced
into the valley of the Mississippi by the "Western Company." In 1799 it
was among the cultivated crops of the Pimos Indians of the Gila River,
New Mexico.
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