Notebooks of Leonardo da Vinci

_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.