DIETETICS. 
stroys its texture, dissolves its particles, 
and disposes them to change their nature 
and become animalized. Spallanzani thinks, 
that tliis gastric fluid traced in the gizzard, 
proceeds chiefly from the oesophagus ; the 
chyme he found to be a semifluid pulta- 
ceous mass, of a whitish yellow colour : tlie 
transparenc 5 ' of this gastric juice, in a state 
of purity, is little inferior to water ; it is 
fluid, and a little bitterish and saline; it 
retains, out of the body, when warm, the 
power of dissolving animal and vegetable 
substances ; but it must be fresh, for if 
kept in vessels, particularly if open, it loses 
its efl5cacy ; it must not have been used for 
experiments, and likewise a heat, equal to 
tliat of the bird, is necessaiy, otherwise it 
has no more effect than water. 
The ruminating animals of the third class, 
such as sheep, oxen, &c. very much resem- 
ble this class of birds in their manner of di- 
gesting substances; in both, the gastric 
fluid requires an agent capable of breaking 
down the food, before it can dissolve it. 
The hay and grass, in the ruminating tribe, 
descend immediately into the fii’st and se- 
cond stomachs, in nearly the same state as 
when first bronzed : here they ai-e softened 
by the juices, as seeds are in the craws of 
birds with gizzards ; but as the stomachs of 
these quadrupeds have no triturating power, 
and the aliment requires trituration, it as- 
cends, in consequence of a gentle stimulus 
to vomit, into the cavity of the mouth, 
where, by means of rumination, it is put in- 
to the same state previous to being digested 
by the gastric fluid, as happens to the food 
in the stomachs of granivorous fowls, after 
they have been properly triturated by the 
gastric muscles. 
Animals with intermediate stomachs, 
such as ravens, crows, herons, &c. have 
muscular stomachs, which are by no means 
eijual in force to the stomachs of the first 
class, but much more so than those of the 
third class. These animals possess the pri- 
vilege of returning substances they are in- 
capable of digesting, at least every nine, 
and in general every two or three hours ; 
they are omnivorous. Their gastric juice 
does not dissolve whole seeds, they there- 
fore bruise them with their beak and feet, 
and they are dissolved in twenty-four hours ; 
it soon dissolves flesh and cartilage, but not 
bone. The fluid in the oesophagus, Spallan- 
zani found inconsiderable as a menstruum, 
when compared with that of the stomach, 
since the first was six hours in dissolving two 
parts of flesh, and the second one hour only 
in dissolving six parts ; consequently the 
cesophagal liquor in the craws of the galli- 
naceous, is different from that in this class. 
The resemblances between the gastric flu- 
ids of these two classes may be reduced to 
five : 1st, These fluids, besides being alike 
in colour, are always salt and bitter, which 
bitterness proceeds from the bile regurgi- 
tating through the pylorus into the stomach. 
2dly, They are the immediate agents of di- 
gestion, both in the muscular and interme- 
diate stomachs, independently of tritura- 
tion. 3dly, The fluids act in the stomachs 
of these two classes of birds in the same 
manner, in the solution of the food ; they first 
soften, and next convert the surface into a 
jelly, then produce the same effect on the 
intermediate parts, insinuating themselves 
gradually into its substance until it is com- 
pletely dissolved. 4thly, They do not en- 
tirely lose their solvent power as soon as 
taken out of the stomach, provided they be 
heated to a proper degree. Sthly, The ori- 
gins whence tliese fluids spring are nearly 
the same, viz. the follicular glands with 
which their organs abound. With respect 
to the differences, they are in part reducible 
to the inferior efficacy of the gastric fluid 
in muscular, to that of the same fluid in in- 
termediate stomachs. The gastric juice of 
the first is incapable of dissolving the same 
aliment that the latter readily dissolves ; 
likewise, the food which each kind of gas- 
tric juice decomposes and digests, is sooner 
subject to this change from that which be- 
longs to intermediate stomachs : hence, ar- 
tificial digestion succeeds much sooner 
with the first than the second. The same 
inefficacy that the gastric juices of birds 
with muscular stomachs shows in the solu- 
tion of aliments of a firm texture, extends 
also to their cesophagal juices in the solu- 
tion of soft substances; notwithstanding 
the latter are tolerably well decomposed 
by the cesophagal juice of birds with inter- 
mediate stomachs. Another very striking 
difference is, the prodigious force of tritu- 
ration in muscular stomachs, and the weak- 
ness of the other, which greatness of 
strength was necessary in birds whose foo 1 
is of considerable firmness, as seeds. 
Animals with membranous stomachs, such 
as frogs, newts, snakes, fishes, ruminat- 
ing animals ; carnivorous birds and beasts, 
as the eagle, falcon, man, dog, cat, &c. this 
class is infinitely more numerous than the 
two former; it comprehends nearly all the 
quadrupeds, fishes, reptiles, birds of prey, 
and the greater part of insects. 
From Spallanzani’s experiments it ap- 
peafs, that carnivorous birds do not dissolve 
