DIETETICS. 
vegetables, and throw up the indigestible 
part every twenty-four hours ; that nature 
in these animals, whose digestion depends 
on the gastric juice alone, without any pre- 
vious mastication or trituration, has pro- 
vided them with a much larger quantity of 
it than the other classes ; that digestion is 
in proportion to the quantity of this fluid ; 
that the gastric juice of the luminating class 
has no ettect in dissolving plants, unless 
they have been previously macerated, and 
ground by the teeth; that its colour in 
sheep is green, and yellow in cows ; that 
owls digest flesh and bones, but not grain ; 
that their gastric juice evaporates sooner 
than water ; that, that of the eagle dissolves 
bread and bone ; its colour is cineritious, 
and it digests animal and vegetable matters 
out of the body; that a wood- pigeon may 
be brought by degrees to live on flesh ; that 
the owl and falcon do not digest bread ; 
that the gastric juice of the dog dissolves 
the enamel of the teeth ; and that tritura- 
tion is necessary in the ruminating ordei-, 
and man, which is produced by the teeth, 
as in gallinaceous fowls by the gizzard ; but 
in other animals, as in the frog, newt, ser- 
pents, and birds of prey, trituration does not 
contribute to digestion : hence, in every or- 
der of animals, the gastric juice is the princi- 
pal cause of digestion, and it agrees in evei-y 
class in many properties, and differs in others. 
In the frog, the newt, scaly fishes, and 
other cold animals, it produces digestion in 
a temperature nearly equal to that of the 
atmosphere. In warm animals it is incapa- 
ble of dissolving the aliment in a degree of 
heat lower than that of these animals. In 
warm animals the food is digested in a few' 
hours, whereas in the opposite kind it re- 
quires several days, and even weeks, parti- 
cularly in serpents ; likewise, the gastric 
juice of the gallinaceous class can only dis- 
solve bodies of a soft and yielding texture, 
and previously triturated ; whilst in others, 
as serpents, the heron, birds of prey, and 
the dog, it decomposes substances of great 
tenacity, as ligaments and tendons ; and 
even of considerable hardness, as the most 
compact bone ; man belongs to this class, 
but his gastric juice seems to have no ac- 
tion on the hardest kind of bones. Some 
species likewise are incapable of digesting 
vegetables, as birds of prey ; but man, the 
dog, cat, crows, &c. dissolve tire individuals 
of both kingdoms alike, and are omnivo- 
rous, and in general their gastric juices pro- 
duce these effects out of the body ; hence, 
the dissolving power of this fluid depends 
on the difference of the nourishment, and 
by some authors it has been said to be the 
cause of hunger and of the difference in the 
choice of the particular aliment ; by which 
power the carnivorous only enjoy flesh ; 
the granivorous and ruminating, only vege- 
table aliments, and no flesh ; but man and 
the omnivorous, both vegetable and animal 
substances. It is, however, asserted by 
Carradori, as decided, tiiat nocturnal birds 
of prey are capable of digesting vegetables : 
it results from his experiments, that they 
also support themselves very well with this 
nourishment, in spite of their repugnance 
to it. If this be the case, the opinion is er- 
roneous, that the gastric juice of these birds 
has only an affinity with animal substances ; 
and what he has established, viz. that carni- 
vorous animals find a nutriment in the pro- 
ducts of plants, was already rendered pro- 
bable by the discovery of Fourcroy, of the 
existence of gluten, albumen, and gelatin 
in the vegetable tribes. Spallanzani, how- 
ever, proves the insufficiency of Carradori’s 
experiments, as the owl died when con- 
fined to vegetable food. The time, more- 
over, requisite for digestion is different in 
different animals ; in many it does not ex- 
ceed five or six hours, and in some it is 
much shorter. 
From the numerous experiments of Gosse 
of Geneva upon digestion, and the action 
which the gastric juice has upon different 
substances, great light has been afforded us 
upon this interesting subject. He informs 
us, that in about one hour and a half after 
the food is taken into the stomach, it is 
changed into a pultaceous mass ; the gas- 
tric juice, likewise, renders it fluid without 
altering its nature ; and when digestion is 
properly carried on there is no appearance 
of acidity or alkalescence; the food does 
not ferment, and the process of digestion is 
not completed until the space of between 
two and three hours has elapsed. The 
chyme which arises from aliments taken ei- 
ther from the animal or vegetable kingdom 
is the same ; they both are by the gastric 
fluid converted into the same substance, 
which is in consequence, most probably, of 
their both containing gelatin, &c. : if, how- 
ever, the digesting solvent is not in suffi- 
cient quantity, or is in a diseased state, the 
acetous fermentation will take place in ve- 
getable, and the putrid in animal matter ; 
hence milk, vegetable matter containing 
sugar, wine, and even spirits, will degene- 
rate, when left to their spontaneous changes 
in the stomach, to a very strong acid, and 
sooner, sometimes, than out of the body, 
perhaps from the heat,' &c. j all oily sub- 
