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Of the first he particularly considers the j 
phoc® or seal tribe ; and endeavours to show, 
that none of them can live chiefly in the wa- 
ter, but that their chief enjoyment of the 
functions of life is on shore. These animals, 
he observes, are really quadrupeds ; but as 
their chief food is fish, they are under the 
necessity of going out to sea to hunt their 
prey, and to great distances from shore; 
taking care that, however great the distance, 
rocks or small islands are at hand, as resting- 
places when they are tired, or when then- 
bodies become too much macerated in the 
water. lie proceeds : It is well known, that 
the only essential difference (as to the general 
structure of the heart) between amphibious 
and mere land animals, or such as never go 
into the water, is, that in the former the oval 
hole remains always open. Now, in such as 
are without this hole, if they were to be im- 
mersed in water but for a little time, respira- 
tion would cease, and the animal must die. 
There are three necessary and principal uses 
of respiration in all land animals, and in those 
kinds that are counted amphibious. The 
first is, that of promoting the circulation of the 
blood through the whole body and extremi- 
ties. In real fishes, the force of the heart is 
alone capable of sending the blood to every 
part, as they afe not furnished with limbs or 
extremities ; which, being so remote from 
the heart, have need of such assistance, 
otherwise the circulation would be very lan- 
guid in these parts. Thus we see, that in 
persons subject to asthmatic complaints, the 
circulation grows languid, the legs grow cold 
and oedematous, and other parts suffer by the 
defect in respiration. A second use of breath- 
ing is, that, in inspiration, the variety of par- 
tides, of different qualities, which float always 
in the air, might be drawn into the lungs, to 
be insinuated into the mass of blood, being 
highly necessary to contemperate and cool 
the agitated mass, and to contribute refined 
pabulum to the liner parts of it, which, meet- 
ing with the daily supply of chyle, serves to 
assimilate and more intimately mix the mass, 
and render its constitution the fitter for sup- 
porting the life of the animal. Therefore it 
is, that valetudinarians, by changing foul or 
unwholesome air for a free, good, open air, 
often recover from lingering diseases. A 
third principal use of respiration is, to pro- 
mote the exhibition of voice in animals ; 
which all those that live on the land do ac- 
cording to their specific natures. From these 
considerations it appears, that the phoc® of 
every kind are under an absolute necessity 
of making the land their principal residence. 
But there is another very convincing argu- 
ment why they reside on “shore the greatest 
part of their time, viz. that the flesh of these 
creatures is analogous to that of other 
land animals ; and therefore, by over-long 
maceration, added to the fatigue of their 
chasing their prey, they would suffer such a 
relaxation as would destroy them. It is well 
known, that animals which have lain long 
under water, are reduced to a very lax and 
even putrid state ; and the phoca must bask 
in the air on shore. Let us now examine by 
what power these animals are capable of re- 
maining longer under water than land animals. 
Ail these have the oval hole open between 
the right and left auricles of the heart, and in 
many the canalis arteriosus also; and while 
the phoca remains under water, which he 
may continue ah hour or two, more or less, 
his respiration is stopped ; and tire blood, not 
finding the passage through the pulmonary 
artery free, rushes through the arterial canal, 
being a short passage to the aorta, and thence 
to every part of the body, maintaining the 
circulation ; but upon rising to come ashore, 
the blood finds its passage again through the 
lungs the moment he respires. Thus the 
foetus in utero, during its confinement, hav- 
ing the lungs compressed, and consequently 
the pulmonary arteries and veins impervious, 
has the circulation of the blood carried on 
through the oval hole and the arterial canal. ■ 
Now so far the phoca in the water, and the 
foetus in utero, are analogous ; but they differ 
in other material circumstances. One is, 
that the foetus having never respired, remains 
sufficiently nourished by the maternal blood 
circulating through him, and continues to 
grow till the time of his birth, without any 
want of respiration, during nine months con- 
finement ; the phoca, having respired the mo- 
ment of his birth, cannot live very long with- 
out it, for the reasons given before ; and this 
hole and canal would be closed in them, as it 
is in land animals, if the dam did not, soon 
after the birth of the cub, carry him so very 
frequently into the .water to teach him ; by 
which practice these passages are kept open 
during life, otherwise they would not be ca- 
pable of attaining the food designed for them 
by Providence. Another difference is, that 
the phoc®, as was said before, would be relax- 
ed by maceration in remaining too long in the 
water ; whereas the foetus in utero sutlers no 
injury from continuing its full number of 
months in the fluid it swims in : the mason is, 
that water is a powerful solvent, and penetrates 
the pores of the skins of land animals, and in 
time can dissolve them; whereas the liquor 
amnii is an insipid soft fluid, impregnated 
with particles more or less mucilaginous, and 
utterly incapable of making the least altera- 
tion in the cutis of the foetus. Otters, bea- 
vers, and some kinds of rats, go occasionally 
into the water for their prey, but cannot re- 
main very long under water. “ I have often 
gone to shoot otters (says our author), and 
watched all their motions : I have seen one of 
them go softly from a bank into the river, and 
dive down ; and in about two minutes rise, at 
10 or 15 yards from the place he went in, with 
a middling salmon in his mouth, which he 
brought on shore : I shot him, and saved the 
fish whole.” Now, as all foetuses have these 
passages open, if a whelp of a true water-spa- 
niel was, immediately after its birth, served as 
the phoca does her cubs, and immersed in 
water, to stop respiration for a little time every 
day, it is probable tiiat the hole and canal 
would be kept open, and the dog be made 
capable of remaining as long under water as 
the phoca. Frogs, how capable soever of re- 
maining in the water, yet cannot avoid living- 
on land, for they respire; and if a frog is 
thrown into a river, he makes to the shore as 
fast as he can. The lizard kind, such as may 
be called water lizards, are all obliged to come 
to land, in order to deposit their eggs, to rest, 
and to sleep. Even the crocodiles, who dwell 
much in rivers, sleep and lay their eggs on 
shore ; and, while in the water, are compelled 
to rise to the surface to breathe ; yet, from the 
texture of his scaly covering, he is papable of 
remaining in the water longer by far than any 
species of the phoca, whose skin is analogous 
7 1 
to that of a horse or cow. The hippopotamus 
who wades into the lakes or rivers, is a qua- 
druped, and remains under the water a con- 
siderable time ; yet his chief residence is upon 
land, and he must come on shore for respira- 
tion. The testudo, or sea tortoise, though he 
goes out to sea, and is often found far from 
land, yet being a respiring animal, cannot re- 
main long under water. He has indeed a 
power of rendering himself specifically heavier 
or lighter than the water, and therefore can 
let himself down to avoid an enemy or a storm: 
yet lie is under a necessity of rising frequently 
to breathe, for reasons given before ; and his 
most usual situation, while at sea, is upon the 
surface of the water, feeding upon the various 
substances that float in great abundance every 
where about him. These animals sleep se- 
curely upon the surface, but not under water, 
and can remain longer at sea than any other 
of this class, except the crocodile, because, as 
it is with the latter, his covering is not in 
danger of being too much macerated. 
1 lie second division of amphibious animals, 
according to Dr. Parsons, comprehends such 
as chiefly inhabit the waters, but occasionally 
goon shore. These are but of two kinds ; the 
eels, and water serpents, or snakes of every 
kind. It is their form that qualifies them for 
loco-motion on the land, and they know then- 
way back to the water at will ; for by their 
structure they have a strong peristaltic mo- 
tion, by which they can go forward at a pret- 
ty good rate; whereas all other kinds of fish, 
whether vertical or horizontal, are incapable of 
a voluntary loco-motion on shore ; and there- 
fore, as soon as such fish are brought out of the 
water, after having flounced a w hile, they lie 
motionless, and soon die. Let us now exa- 
mine into the reason why these vernacular 
fish, the eel and serpent kinds, can live a 
considerable time on land, and the vertical 
and horizontal kinds die almost immediately 
when taken out of the water -. and, in this re- 
search, we shall come to know' what analogy 
there is between land animals and those of tire 
waters. All land animals have lungs, and can 
live no longer than while these are inflated by 
the ambient air, and alternately com pressed 
for its expulsion ; that is, while respiration i* 
duly carried on, by a regular inspiration and 
exspiration of air. In like manner, the fish in 
general have, instead of lungs, gills or bron- 
chi® : and as, in land animals, the lungs have 
a larger portion of the mass of blood circu- 
lating through them, which must be stopped 
if the air has not a free ingress and egress into 
and from them ; so, in fish, there is a great 
number of blood vessels that pass through the 
bronchi®, and a great portion of their blood 
circulates through them, which must in like 
manner be totally stopped, if the bronchi® afe 
not perpetually wet with wafer. So that, as 
the air is to the lungs in land animals, a con- 
stant assistant to the circulation; s6 is the 
water to the bronchi® of those of the rivfots 
and seas : for when these are out of the water, 
tire bronchi® very soon grow crisp and dry, 
the blood-vessels are shrunk, and the blood “is 
obstructed in its passage; so, when the former 
are immersed in water, or otherwise prevented 
from having respiration, the circulation ceases, 
and the animal die*. Again, as land-animals 
would be destroyed by too much maceration 
in water, so fishes would, on the other hand. 
Ire ruined by too much exsiccation ; the latter 
being, from their 'general structure andfoonsti- 
