The Cambria freeman. [volume] (Ebensburg, Pa.) 1867-1938, 1889-08-09

LGES showed lllE-lSt-LhEs IL i~1--
persisted for some time after, the de-
velopmeut OF the legs but its disap-
pearance-by a process of absorption
finally took place with great rapid
ity, occupying only two or three days.
The giIIs appear to wither away al
about the time of the disappearance OF
the tail. At any rate at this time the
animal is first seen TO come TO the
surface for e,r. For a limited period
It appears to have the use both OF
gills and lungs 1t is q curious conGi-
tion at this time, when one set Of
breathing organs is shriveling up at
an equal pace with the development
of the other set. Not less remarkable
IS the fact that at this juncture the
creature changes its diet-passin,~
from a herbivorous to a caruivOrOus
animal Teeth also appear in the
mouth Con the upper jaw only and the
long. heshv tongue, attached at its front
end and loose behind. attaius complete
growth. The opening of the mouth,
too. becomes enormously enlarged, ex-
tending far back at the sides Of the
head.
But while these transformations are
truly remarkable it Is well 10 keep in
mind that, after all, they are not essen
TALLY different from those through
which other animals pass in their
bodily Development Take, for exam
pie, n bird. The changes which take
place within the egg during the early
period Of incubation are quite the same
ir their general nature as those which
the frog passes through after IL has
completed the period OF incubation
GTLc frog matches from its egg by the
heat Of the SUM. The chief difference
is that in the bird these changes are
completed during the egg stage. the
animal leaving the egg with all its
class characters In perfection. But IN
the frog, NJ the time the young leaves
the EGG il is in the fish stage; that is
TO sav, il has the characteristics of a
class at least two grades below its own
proper class. And 50 1t must go on in
its development after having passed
the egg stage; and as these final stages
take place before our eyes they attract
our attention, aud are in danger Of
leading US TO suppose that the develop
mental history of the frog is peculiar
and anomalous.
The frog affords an example fthCse
animals which secure protection from
the attacks Of their enemies by MIN
licking the color Of their surroundings.
BY some physiological process. the
nature Of which is not well understood.
they are able to vary the color of the
pigment of the skin IN correspondence
TO the color OF their surroundings.
Thus, when they sit in the grass on
the bank Of a pool or stream, they
change their color TO green, and thus
are less likely TO be seen by birds and
snakes, which are their chief enemies
The frogs differ from most animals
in possessing no distinct organs OF de-
Tense. But his powerful leaping mus
cles stand him in good stead as a
means Of escape, both when on the
shore and when in the water, in the
latter case enabling him to swim with
great quickness.
The sense-organs of the frog are
well developed and are quick in their
action. The external part Of the ear
IS very noticeable, appearing as a
round, dark space Just behind the eyes
1t corresp ponds TO the tympanum or
ear-drum of higher animals There
are deIicately formed olfactory cells in
the nasal cavities, Indicating that the
sense of smell is fairly acute. The
ewes are well formed and are provided
with lids, the lower one alone is freely
movable. II the eye be touched it is
drawn inward under the upper lid and
at the same time the lower lid asceuds
TO close the eye
The manner in which breathing is
effected in the frog is peculiar. The
lungs are simple sacks, similar to the
m-bladders of fishes. except that
they are dived internally into minute
chambers or cells They are not sus-
pended in 4 chest cavity, but hang
loosely in the general cavity Of the
body. Hence they can not be filed
with air by means Of movements OF the
sides OF the body. as is the case with
the higher vertcbrated animals. But
a mechanism Of 4 similar principle Of
operation is found in the floor Of the
mouth This is capable of being
lowered by the muscular action, thus
greatly enlarging the mouth cavity.
/ The vacuum thus formed is filed by
/ air passing in through the nostriIs.
/ These passages are then closed, and
I the floor OF the mouth raised, the air
I thus being forced into the lungs The
action is therefore not dissimiIar to
| that Of a force-pump. The lungs
/ having been filed, expiration takes
/ place by the mere reaction OF their
/ elastic tissue, as in the higher animals
! The skin appears to be a necessary
Z accessory organ in breathing. At any
, rate a frog soon dies when kept in a
! dry place, the explanation seeming 10
| be that the pores Of the skin are closed
| so that the blood is not sufficiently
/ purified. In winter they breathe
I through the skin alone And it has
I been shown that in summer, when
/ their vital processes are in the highest
I state OF activity, they live for long
/ time, when confined to breathing by
/ the skin alone, the nostriIs having
been stopped or the lungs themselves
removed An experiment is reported
/ in which q frog lived five weeks after
having thus been deprived OF its lungs
The winter habits Of the frog are
/ not dissimilar TO those of other rep
| tilian animals. 1t burrows into the
mud at the bottom of the pool and re-
mains in a torpid condition until
! spring. The vital processes appear to
be sustained during the time by nutri-
! ment stored up in a special internal
! organ called the fat-body-
AS is well known, the spring is the
season of the greatest activity with
! these animals The discordant croaks
of the male frog are a Characteristic
sound of the warm spring night In
some species, as subserv lent 70 the
production Of voice, there are large