The Notebooks of Leonardo Da Vinci — Complete
_a_. hair
_n_. skin
_c_. muscle
_m_. fascia
_o_. skull _i.e._ bone
_b_. dura mater
_d_. pia mater
_f_. brain
_r_. pia mater, below
_t_. dura mater
_l_. rete mirablile
_s_. the occipitul bone.
[Footnote: See Pl. CVIII, No. 3.]
Physiological problems (814. 815).
814.
Of the cause of breathing, of the cause of the motion of the heart,
of the cause of vomiting, of the cause of the descent of food from
the stomach, of the cause of emptying the intestines.
Of the cause of the movement of the superfluous matter through the
intestines.
Of the cause of swallowing, of the cause of coughing, of the cause
of yawning, of the cause of sneezing, of the cause of limbs getting
asleep.
Of the cause of losing sensibility in any limb.
Of the cause of tickling.
Of the cause of lust and other appetites of the body, of the cause
of urine and also of all the natural excretions of the body.
[Footnote: By the side of this text stands the pen and ink drawing
reproduced on Pl. CVIII, No. 4; a skull with indications of the
veins in the fleshy covering.]
815.
The tears come from the heart and not from the brain.
Define all the parts, of which the body is composed, beginning with
the skin with its outer cuticle which is often chapped by the
influence of the sun.
II.
ZOOLOGY AND COMPARATIVE ANATOMY.
The divisions of the animal kingdom (816. 817).
816.
_Man_. The description of man, which includes that of such creatures
as are of almost the same species, as Apes, Monkeys and the like,
which are many,
_The Lion_ and its kindred, as Panthers. [Footnote 3: _Leonza_--wild
cat? "_Secondo alcuni, lo stesso che Leonessa; e secondo altri con
piu certezza, lo stesso che Pantera_" FANFANI, _Vocabolario_ page
858.] Wildcats (?) Tigers, Leopards, Wolfs, Lynxes, Spanish cats,
common cats and the like.
_The Horse_ and its kindred, as Mule, Ass and the like, with incisor
teeth above and below.
_The Bull_ and its allies with horns and without upper incisors as
the Buffalo, Stag Fallow Deer, Wild Goat, Swine, Goat, wild Goats
Muskdeers, Chamois, Giraffe.
817.
Describe the various forms of the intestines of the human species,
of apes and such like. Then, in what way the leonine species differ,
and then the bovine, and finally birds; and arrange this description
after the manner of a disquisition.
Miscellaneous notes on the study of Zoology (818-821).
818.
Procure the placenta of a calf when it is born and observe the form
of the cotyledons, if their cotyledons are male or female.
819.
Describe the tongue of the woodpecker and the jaw of the crocodile.
820.
Of the flight of the 4th kind of butterflies that consume winged
ants. Of the three principal positions of the wings of birds in
downward flight.
[Footnote: A passing allusion is all I can here permit myself to
Leonardo's elaborate researches into the flight of birds. Compare
the observations on this subject in the Introduction to section
XVIII and in the Bibliography of Manuscripts at the end of the
work.]
821.
Of the way in which the tail of a fish acts in propelling the fish;
as in the eel, snake and leech.
[Footnote: A sketch of a fish, swimming upwards is in the original,
inserted above this text.--Compare No. 1114.]
Comparative study of the structure of bones and of the action of
muscles (822-826).
822.
OF THE PALM OF THE HAND.
Then I will discourse of the hands of each animal to show in what
they vary; as in the bear, which has the ligatures of the sinews of
the toes joined above the instep.
823.
A second demonstration inserted between anatomy and [the treatise
on] the living being.
You will represent here for a comparison, the legs of a frog, which
have a great resemblance to the legs of man, both in the bones and
in the muscles. Then, in continuation, the hind legs of the hare,
which are very muscular, with strong active muscles, because they
are not encumbered with fat.
[Footnote: This text is written by the side of a drawing in black
chalk of a nude male figure, but there is no connection between the
sketch and the text.]
824.
Here I make a note to demonstrate the difference there is between
man and the horse and in the same way with other animals. And first
I will begin with the bones, and then will go on to all the muscles
which spring from the bones without tendons and end in them in the
same way, and then go on to those which start with a single tendon
at one end.
[Footnote: See Pl. CVIII, No. 2.]
825.
Note on the bendings of joints and in what way the flesh grows upon
them in their flexions or extensions; and of this most important
study write a separate treatise: in the description of the movements
of animals with four feet; among which is man, who likewise in his
infancy crawls on all fours.
826.
OF THE WAY OF WALKING IN MAN.
The walking of man is always after the universal manner of walking
in animals with 4 legs, inasmuch as just as they move their feet
crosswise after the manner of a horse in trotting, so man moves his
4 limbs crosswise; that is, if he puts forward his right foot in
walking he puts forward, with it, his left arm and vice versa,
invariably.
III.
PHYSIOLOGY.
Comparative study of the organs of sense in men and animals.
827.
I have found that in the composition of the human body as compared
with the bodies of animals the organs of sense are duller and
coarser. Thus it is composed of less ingenious instruments, and of
spaces less capacious for receiving the faculties of sense. I have
seen in the Lion tribe that the sense of smell is connected with
part of the substance of the brain which comes down the nostrils,
which form a spacious receptacle for the sense of smell, which
enters by a great number of cartilaginous vesicles with several
passages leading up to where the brain, as before said, comes down.
The eyes in the Lion tribe have a large part of the head for their
sockets and the optic nerves communicate at once with the brain; but
the contrary is to be seen in man, for the sockets of the eyes are
but a small part of the head, and the optic nerves are very fine and
long and weak, and by the weakness of their action we see by day but
badly at night, while these animals can see as well at night as by
day. The proof that they can see is that they prowl for prey at
night and sleep by day, as nocturnal birds do also.
Advantages in the structure of the eye in certain animals (828-831).
828.
Every object we see will appear larger at midnight than at midday,
and larger in the morning than at midday.
This happens because the pupil of the eye is much smaller at midday
than at any other time.
In proportion as the eye or the pupil of the owl is larger in
proportion to the animal than that of man, so much the more light
can it see at night than man can; hence at midday it can see nothing
if its pupil does not diminish; and, in the same way, at night
things look larger to it than by day.
829.
OF THE EYES IN ANIMALS.
The eyes of all animals have their pupils adapted to dilate and
diminish of their own accord in proportion to the greater or less
light of the sun or other luminary. But in birds the variation is
much greater; and particularly in nocturnal birds, such as horned
owls, and in the eyes of one species of owl; in these the pupil
dilates in such away as to occupy nearly the whole eye, or
diminishes to the size of a grain of millet, and always preserves
the circular form. But in the Lion tribe, as panthers, pards,
ounces, tigers, lynxes, Spanish cats and other similar animals the
pupil diminishes from the perfect circle to the figure of a pointed
oval such as is shown in the margin. But man having a weaker sight
than any other animal is less hurt by a very strong light and his
pupil increases but little in dark places; but in the eyes of these
nocturnal animals, the horned owl--a bird which is the largest of
all nocturnal birds--the power of vision increases so much that in
the faintest nocturnal light (which we call darkness) it sees with
much more distinctness than we do in the splendour of noon day, at
which time these birds remain hidden in dark holes; or if indeed
they are compelled to come out into the open air lighted up by the
sun, they contract their pupils so much that their power of sight
diminishes together with the quantity of light admitted.
Study the anatomy of various eyes and see which are the muscles
which open and close the said pupils of the eyes of animals.
[Footnote: Compare No. 24, lines 8 and fol.]
830.
_a b n_ is the membrane which closes the eye from below, upwards,
with an opaque film, _c n b_ encloses the eye in front and behind
with a transparent membrane.
It closes from below, upwards, because it [the eye] comes downwards.
When the eye of a bird closes with its two lids, the first to close
is the nictitating membrane which closes from the lacrymal duct over
to the outer corner of the eye; and the outer lid closes from below
upwards, and these two intersecting motions begin first from the
lacrymatory duct, because we have already seen that in front and
below birds are protected and use only the upper portion of the eye
from fear of birds of prey which come down from above and behind;
and they uncover first the membrane from the outer corner, because
if the enemy comes from behind, they have the power of escaping to
the front; and again the muscle called the nictitating membrane is
transparent, because, if the eye had not such a screen, they could
not keep it open against the wind which strikes against the eye in
the rush of their rapid flight. And the pupil of the eye dilates and
contracts as it sees a less or greater light, that is to say intense
brilliancy.
831.
If at night your eye is placed between the light and the eye of a
cat, it will see the eye look like fire.
Remarks on the organs of speech
(832. 833).
832.
_a e i o u
ba be bi bo bu
ca ce ci co cu
da de di do du
fa fe fi fo fu
ga ge gi go gu
la le li lo lu
ma me mi mo mu
na ne ni no nu
pa pe pi po pu
qa qe qi qo qu
ra re ri ro ru
sa se si so su
ta te ti to tu_
The tongue is found to have 24 muscles which correspond to the six
muscles which compose the portion of the tongue which moves in the
mouth.
And when _a o u_ are spoken with a clear and rapid pronunciation, it
is necessary, in order to pronounce continuously, without any pause
between, that the opening of the lips should close by degrees; that
is, they are wide apart in saying _a_, closer in saying _o_, and
much closer still to pronounce _u_.
It may be shown how all the vowels are pronounced with the farthest
portion of the false palate which is above the epiglottis.
833.
If you draw in breath by the nose and send it out by the mouth you
will hear the sound made by the division that is the membrane in
[Footnote 5: The text here breaks off.]...
On the conditions of sight (834. 835).
834.
OF THE NATURE OF SIGHT.
I say that sight is exercised by all animals, by the medium of
light; and if any one adduces, as against this, the sight of
nocturnal animals, I must say that this in the same way is subject
to the very same natural laws. For it will easily be understood that
the senses which receive the images of things do not project from
themselves any visual virtue [Footnote 4: Compare No. 68.]. On the
contrary the atmospheric medium which exists between the object and
the sense incorporates in itself the figure of things, and by its
contact with the sense transmits the object to it. If the
object--whether by sound or by odour--presents its spiritual force
to the ear or the nose, then light is not required and does not act.