DID 
ceptacle honey-combed, dividing into parts 
which retain the seeds ; down chaffy, many- 
leaved. There are two species, D. carno- 
sa, succnlent-leaved didelta, has an herba- 
ceous stem, very much branched, ereet, 
round, nearly eighteen inches high ; leaves 
alternate, sessile, spreading, acute, atte- 
nuated at the base, quite entire, woolly 
above, beneath one-nerved, veinless, two 
or three inches long, six or eight lines 
broad; in the stove permanent; flowers so- 
litary, terminating on long peduncles, yel- 
low; annual, but in the stove it will last 
some years, becoming shrubby, which is of- 
ten the case with annual plants. It is a na- 
tive of the Cape ; also D. spinosa, where 
they flower about July. 
DIDUS, the dodo, in natural history, a 
genus of birds of the order Gallinae. Ge- 
neric character : bill large, and, at the mid- 
*lle of the upper mandible, bending in- 
wards, marked with two oblique ribs, and 
considerably hooked at the tip ; nostrils si- 
tuated in tlie middle of the bill, and ob- 
liquely near’ the edge; legs short, thick, 
and in the upper part feathered ; feet cleft ; 
toes three forward and one backward ; no 
tail. There are three species. D. ineptus, 
or the hooded dodo, is nearly three feet 
long, and inhabits the islands of Bourbon 
and France. Its pace is slow; its body 
round and fat ; its weight, occasionally, fifty 
pounds ; and though sometimes eaten, ac- 
cording to Herbert, is considered as indif- 
ferent food. Its head appears to be covered 
with a black cowl, and, altogether, its figure 
is singularly curious and grotesque. In Mr. 
Grant’s history of the Mauritius, however, 
this bird is stated to be no longer found in 
that island or Bourbon ; and, most proba- 
bly, is to be classed among those species 
which have been destroyed, through the 
ease with which they were taken : on unin- 
habited islands, however, it is added, the 
hooded dodo may possibly yet be found. 
The observation of Mr. Grant, with re- 
spect to the dodo, must be supposed to ap- 
ply to all those of the species, of which, in- 
deed, the one above-mentioned is given 
upon much better authority than attaches 
to the other two. Latham thinks it not im- 
probable that these two differed from the 
first only in age or sex. See Aves, Plate 
VI. fig. 2, 
DIDYNAMIA, in botany, the name of 
the fourteenth class in Linna;us’s method, 
consisting of plants with hermaphrodite 
flowers, which have four stamina or male 
organs, two of which are long, and two short. 
DIE 
DIETETICS, the science or philosophy 
of diets : that which teaches us to adapt 
particular foods to particular organs of 
digestion, or to particular states of the same 
organs ; so that the greatest possible por- 
tion of nutriment may be extracted from 
a given quantity of nutritive matter ; or a 
sufficient portion may be obtained with the 
least possible quantity of organic action 
and exhaustion. In this sense the science 
,of dietetics embraces a knowledge as well 
of the organs and economy of digestion, as 
of the substances to be digested ; and un- 
der this division we shall treat of it in the 
sketch before qs. 
The organs of digestion differ exceed- 
ingly in different classes of animals ; but in 
all, even in soophytes and infusory worms, 
there is one which answers the purpose of a 
stomach, the most important of all the di- 
gestive organs. In the more perfect ani- 
mals, the salivary glands, the pancreas, and 
the liver, are all said to concur with the 
stomach, and, perhaps, the smaller intes- 
tines in the process of digestion ; and, ac- 
cording to Cruikshank, about a pint of 
gastric, or stpmach secretion, half a pint of 
saliva, half a pint of pancreatic juice, and 
twenty ounces of bile, are ppured into the 
human stomach in the period of every 
twenty-four hours ; while the same process 
is aided by a considerable quantity of sol- 
vent fluid of a different kind secreted 
through the whole length of tlie internal sur- 
faces of the intestines. Yet as some, doubts 
have been entertained as to the relative 
contributions of these differeiit viscera ; and 
as in different classes of animals they vary 
in every possible mode of deficiency, till at 
length, in the lowest orders, we find nothing 
but the stomach itself left to maintain tlie 
entire economy; more especially as wo 
cannot at present enter into the question 
of the relative importance of the rest, we 
shall confine our ob-servations almost ex- 
clusively to the stomach, and shall only 
glance at the collatitious viscera as we may 
perceive it absolutely necessary. 
If we look back into antiquity, we shall 
find that the earliest opinion on the cause 
of digestion was, that of putridity. It was 
by this process that both Hippocrates and 
Empedocles supposed the food w’hen taken 
into the stomach to be reduced to a proper 
state for the support of the animal system. 
Galen and his disciples conceived an idea 
that it was brought about by heat. Van 
Helmont, whose wild conjectures can only 
be accounted for by the spirit and enthn- 
