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The marsupial plague—Young of
the marsupiata horn—What is a marsupial?—Able account by a "Bush
Naturalist."
One of the most extraordinary
phenomena of Australian animal life has been the tremendous increase in
numbers, during late years, of the kangaroos and other kindred marsupials,
in the western interior plains of Queensland. At the period of my visit, at
which we have now arrived, the evil had become one of such enormous
magnitude, that the value of station property had actually deteriorated.
Legislation was cried for, on the subject. The squatters were almost
powerless to stem the overwhelming tide of animal life that cropped bare
every leaf and vestige of grass, and in some places the "marsupial plague,"
as it is called, had threatened altogether to oust the sheep and cattle from
the runs, and, by eating up the whole of the scanty pasture, leave nought
but barren rock and worthless weeds for the subsistence of the flocks and
herds. The newspapers had been full of plans, suggestions, and disquisitions
on the subject, some more or less practical, others wholly visionary.
Fencing-in had been tried, but was too expensive. Hunting with dogs was
found quite inadequate to cope with the evil. Some contended that the
destruction of natives, and the wild native dog, and the stoppage of
destructive bush fires, had done much to allow the animals to increase; but
from whatever cause, the plague was becoming a gigantic evil, and threatened
to interfere most seriously, if not to do away entirely, with the wool
industry. On one run,, for instance, in the Stanthorpe district, it was
computed that there were fully 60,000 head of marsupials, and as every one
of these will eat as much grass as a sheep, the magnitude of the evil can be
seen at a glance. Peak Downs' station, a well-known Queensland run, had been
bought by the present owner some years ago with 40,000 head of sheep, and
already at the time of my visit, more than that number of marsupials, had
been destroyed by the owner.
I have made various
observations, and had come independently to a conclusion of my own on one of
the most disputed points in connexion with the marsupial tribe. But I have
found in the Queenslander, that admirably conducted paper, a contribution on
the subject, so excellent, and written by such a master in the art of
observation, that I think it best to reproduce it for the benefit of my
readers. The writer signs himself "A Bush Naturalist." In connexion with the
overwhelming swarms of these curious animals,—"Now that attention generally
is rivetted upon this extraordinary increase of a wild animal under the
shadow of civilization, a paper on 'What is a marsupial?' may perhaps be
interesting to many of those who are engaged in slaughtering them by
thousands.
"The term Marsupiata, or
Marsupialia, is derived from the word marsupium—a purse or bag—and has
reference to the well-known pouch for carrying the young with which we are
all so familiar in the kangaroos and opossums; but it is not so well known
that many of our marsupial animals have hardly any pouch, and some even none
at all. In the peramelidai genus (bandicoots, &c.) the open end of the pouch
is, strange to say, downwards, the bag itself extending upwards, or exactly
contrary to the way it is in the kangaroo, opossum, kaola, and wombat. In
the dasyuridce genus (native cats, phascogale, &c.) there is no pouch at
all. These carnivorous members of the family give birth to as many as five
or six young at a time, and these, when born, are as immature as those of
the kangaroo, and cling on to the teats of the mother in a similar way—-just
as firmly, too, notwithstanding the lack-of a pouch to protect them. It has
always been a wonder to me, when I have killed a native cat, and seen
half-a-dozen of these delicate little lumps of flesh hanging to the teats by
their mouth alone, how it is that they are not killed, or at least injured,
by contact with the rough ground or the branches of trees as the mother runs
about and hunts for food. One thing I have noticed—that they do not carry
them so long, in proportion, as the kangaroos do their young, but make a
nest instead. In the echidna (porcupine) the pouch is represented only by a
curved wrinkle of the skin; and in the platypus it is quite absent, as also
are the nipples, the milk exuding through exceedingly minute pores of the
mammary gland; and yet these very different genera are all marsupials, the
two latter belonging to the second section of the order—the monotremata.
"There are several
peculiarities which join together this large group of animals—a group of
which Australians may well be proud, for it contains among it members whose
habits are as diversified as are their forms, for some are arboreal, some
terrestrial, some aquatic, some most rapid burrowers, and others are
actually aerial travellers. There are among them herbivorous species, as
also are there cruel carnivora, insect-destroyers, and crab-catchers. They
are a group which comprises many varieties of form quite unknown beyond our
own sunny land—mysteries of anatomy, marvels of Nature's workmanship, which,
when first shown to the old-world scientists, provoked a smile of
incredulity as to their being real. The principal characteristic uniting all
these species together is the fact that they are non-placental. The young of
all other mammals are nourished until they attain to a large size, before
being born, by having this placental connexion with the circulation of the
blood of the mother, which enables the food partaken of by the mother also
to nourish .the young. In the marsupiata this placental connexion is absent,
but the life-germ may be detected in the uterus in a still more immature
state than is seen by the kangaroo-hunters on the nipple. There being no
placenta, it is unattached, and grows by absorption, of its own accord,
seed-like, egglike, till born. In this respect, as well as in several
others, the marsupials approach somewhat closely to the ovoviviparous
creatures.
"Bushman as I am, and having
killed and roughly examined some hundreds of kangaroos, &c., I of course was
strongly inclined to the opiniou expressed by your correspondent, Mr.
M'Arthur (February 8) that the young grew out of the end of the nipple; but
when I came to read how much the subject had been studied by anatomists, I
found the teat theory would not hold. It is a fact that the young can be
found in the first uterus, as stated above, and also that there is no
possible connexion with the external uterus, or pouch.
The only point not proved is
the actual passage from the one to the other. But, supposing that the young
foetus did descend the teat, or that the teat was drawn up, inverted
glove-like for that purpose, it does not overcome the difficulty of how this
immature little lump of flesh manages to fix itself on the outside of the
teat, unless it has the power also to (glove-like) turn itself inside out;
and if the creature descends the birth-teat (as some suppose), and fixes
itself on to a milk-teat, the same difficulty still occurs—i.e., how does it
do it ? Australians must remember that marsupials have been known ever since
the discovery of America, and that for the last hundred years—that is, since
Captain Cook's time, when the kangaroo was discovered—no animals have been
more studied and examined by the anatomist and zoologist; and a bushman's
crude opinion and rough external examination has no weight in opposition to
the anatomical dissections of such men as John Hunter, Sir E. Horne,
Geoffrey Saint Hilaire, Cuvier, De Blainville, Owen, and others. We bushmen
are on the wrong track when we look into the pouch of the kangaroo in order
to elucidate the mystery of the birth of their young; we must turn back and
try a fresh cast—attain some considerable anatomical knowledge, and learn to
dissect —then we shall find that we are travelling over old ground; that
others have long since found out the way which to us is unknown. When such
an authority as Professor Owen, of London—the greatest of living comparative
anatomists, the most learned paleontologist of the day—pledges his word that
the young kangaroo is born on its thirty-ninth day of gestation, and this
from his actual daily examination of a tame doe in the Zoological Gardens in
London, and also after the anatomical dissection of the numbers that have
passed through his hands, we may safely accept his conclusions. The actual
transit of the little one into the pouch was not seen by Mr. Owen, although
he examined the teat daily; it was not till the Thirty-ninth day that it
appeared, and it was then firmly attached to the nipple, and of a length not
exceeding 1 in. and 2 inches. The species was the common great kangaroo (Macrojpus
major). Four days after birth, he detached the young one in order to see if
it had the power of regaining the nipple, but after two days he examined the
pouch and found it empty. Every portion of the litter was carefully
searched, in the hopes of finding the foetus, but without success; the
mother, therefore, it was supposed, had destroyed it in consequence of the
disturbance.
"In the Zoological Journal,
vol. v., p. 239, an instance is given of a young foetus which was only a
degree larger than the one detached by Professor Owen, for it was ' only the
size of the last and half the middle joint of one's little finger; its
integuments of a flesh-colour, and so transparent as to permit the higher-coloured
vessels and viscera to shine through them.' This minute specimen, although
it made no effort to regain the teat when held close to it, yet in two
hours' time after it had been experimentally detached had regained it and
was as well as before. In the ' Transactions of the Linneean Society,' vol.
xvi., is mention of a similar experiment on a foetus the size of a rat; and
this also, after two hours' separation, had regained its hold, and was none
the worse.
To the mode of birth of the young marsupial (except of the monotremata), the
only query being as to how this feeble lump of delicate flesh manages to
attach itself so firmly by the mouth to the nipple of the dam. I would ask
your correspondent, Mr. McArthur, whether, in the case of the carnivorous
marsupials (dasyuridce) which I have, as before stated, found with six
young, each hanging to its own nipple, if he supposes all these nipples are
inverted at the time of conception, and that each receives its individual
germ? Without being an anatomist, it is evident to any one that in the case
of the anterior nipples this could not possibly be the case. It is supposed
that the mother takes up the little one in her lips and places it in the
pouch.
"Microzoon,' the scientific
contributor to the Australasian, in 1869 (I think) stated that4 several of
both the American and the Australian marsupials have been watched-at the
time of parturition, and there can be no doubt of the young being brought
forth in the ordinary way of other mammals, taken up by the lips of the
mother, and fixed in this way upon the teat; in the case of the kangaroos,
the female has been seen often holding open the aperture of the pouch, and,
plunging the head to the bottom of it, replacing the young which had been
experimentally detached.5 My own impression is that the nipple is capable of
a certain degree of erectile rigidity (no uncommon thing in mammce), and so
the animal is enabled to pierce the tender mouth of the foetus as held to it
by the lips of the mother. Against this theory of removal by the lips we
must place the peculiarities of the echidna (porcupine). On this subject Mr.
Krefft, late curator of the Sydney Museum, says, The manner in which the
young {echidna) is brought forth and deposited in one of the two small
cavities or pouches on the abdomen, which are destitute of nipple's, is a
wonder to me. In the case of the kangaroo, or even of the clumsy wombat, the
lips may convey the new-born young to the teat; but here is an animal
without lips, and with the stiffest of great unwieldy claws, and yet it has
the means of housing its young, which are about the size of a large tick,
securely in its abdominal receptacle, where nothing secures it but its own
great claws; even in so young a creature, these are already powerfully
developed. As there are no nipples in the echidna, what becomes of the
inverted-nipple theory in-their case? Botanist, in the Queenslander, says
that his black boys say that the echidna lays white eggs, and the platypus
black ones. Perhaps they do, and the young, when they emerge from the egg,
if the mother is at that time lying on the egg, are thus enabled at once to
cling to the abdomen. I believe it is still an open question as to whether
these mono-tremes are oviparous, or bring forth the living young. What are
our lynx-eyed Australian youth about that, although the country has been
settled for a hundred years, they have not found out all about the young of
the echidna and platypus?
The next peculiarity, which
is a most constant characteristic of a marsupial, is the presence of the
marsupial bones. These are two bony pieces extending one on each.side,
upwards and outwards from the pubis, where they converge, and to which they
are joined. These bones are common to both sexes, and only absent, I
believe, in one species—the thylacinus, or tiger-wolf, of Tasmania.
Professor Owen says that both sexes of the marsupial genera in various
ways3 manifest their affinity to the oviparous classes, and also that 4 the
marsupial bones so common in the skeletons of reptiles are limited in the
mammiferous class to this division, in which alone, from the peculiarly
brief period of uterine gestation and the consequent non-enlargement of the
abdomen, their presence might be expected. But these bones serve important
purposes in relation to the generative economy of the marsupiata. In the
female they assist in producing a compression of the mammary gland necessary
for the alimentation of a peculiarly feeble offspring, and they defend the
abdominal viscera from the pressure of the young as these increase in size
during their mammary or marsupial existence, and still more so when they
happen to return to the pouch for shelter. The author (Professor Owen) next
proceeds to point out the uses of these bones in the males, which have
peculiarities corresponding to the pouch in the female— ad characters supra
dictos addantur in maribus situs testium ante penem, et in feminis vagina in
duas canales septo di-visa.'3 These bones are also to be found in tho
subdivision monotremata. The young marsupial has not, when very young, the
power to suck; the milk is ejected by the mother.
"Another distinguishing
characteristic of a marsupial is one on which scientific anatomists lay
great stress, but which to me, I confess, seems unimportant, for no use can
be found for it; it is the celebrated 4 inflected angle of the lower jaw.' I
will quote from Krefft to explain this technical phrase: Let me explain my
words to those who may have the jaw of an opossum or wallaby at hand. The
flat process rising up just from behind the last tooth is called the
"ascending ramus." This bone dips down again and then expands to the right
and left, producing the "condyle," which works against the skull and causes
the jaws to move. At the inside base of this condyle the jaw or mandible
enlarges, spoonlike, forming in kangaroos, phalangers (opossums), and
wombats a deep hollow, and in the carnivorous tribes a hooked process, well
turned in. In the Icaola (native bear) this piece of bone is reduced to a
notch, which is very slightly bent inwards at the tip only.' As the
monotremata (echidna and platypus) are the only exception to this law, the
characteristic is a good and very strange distinguishing point as applied to
our existing marsupials; but I remember reading somewhere that in some of
our gigantic fossil marsupials it is not to be observed. So exclusively is
this trifling variation a feature of ' what constitutes a marsupial' that in
only one other mammal in the whole world— the Madagascar centetee—is it to
be found.6 Another remarkable peculiarity of a marsupial is the permanent
separation of the bones of the skull; they do not anchylose in the adult and
old individual, as do most of the bones of the skull in placental animals7
By this peculiarity our Australian animals show their alliance with the
reptilia, among whom this separation is the common rule.
"In undertaking to write as
to what constitutes a marsupial it is necessary that I should refer to yet
another peculiarity, which,. I must own, is a little beyond my own or the
ordinary bushman's technical knowledge, but which, for the sake of the more
anatomically learned among the Queenslander's many readers, I must not leave
out, or my paper would be incomplete. I will quote from ' "Waterhouse's
Marsupials :' 'Agreeably to this view connected with the ovovi-viparous
generation of the marsupiata, and with an inferiority of intelligence which
Professor Owen observed in these animals in confinement, he was induced to
undertake a careful examination of the brain in the various marsupials, and
the result was a most interesting discovery. Besides the decreased size of
the hemispheres of the brain, and consequent exposure of the cerebellum,
indicative of alow grade of organization, the corpus callosum and septum
lucidum were found to be "entirely wanting in these animals, or at least
existing in only a rudimentary state. Now the corpus .callosum, which is the
principal bond of union between the opposite hemispheres of the brain, had
been regarded as the great characteristic of the brain in the mammalia, and
in fact this commissural apparatus presents the essential difference which
exists between that and the oviparous vertebrate classes.'
"The reader who takes
interest enough in this subject to have followed me will now begin to see 4
what constitutes a marsupial,' and to find, notwithstanding the name, that
the pouch has very little to do with it. First, there is the chief
peculiarity—their being non-placental; then there are those curious
marsupial bones; then there is the apparently useless, but nevertheless
invariably found, inflected angle of the lower jawbone; then there is the
divided state of the bones of the skull; then the small brain and the want
of the corpus callosum and the septum lucidum. The observant reader will
also see that in many respects the order approach nearly to an allianee with
the reptiles, and to the egg-laying vertebrata—an alliance which, in the
division monotremata, is still more clearly to be traced. Many naturalists
have wished to break up the order, distributing them among the other mammals
according to their teeth, toes, opposable thumbs, &c.; but the clever
anatomical investigations of Professor Owen discovered in how many curious
ways the whole group agreed— carnivorous as well as herbivorous, aerial as
well as aquatic, American and Australian representatives; and they are now
admitted to be a distinct grand division of Nature, as are the mammalia, the
birds, or the reptiles." |
