Lionardo da Vinci

Physiology

Physiology 

'The frog instantly dies when the spinal cord is pierced; and previous to this it lived without head without heart or any bowels or intestines or skjn; and here therefore it would seem lies the foundation of movement and life! 

{Experimental investigations of spinal cord and intestines of frog] [with drawing] 

  • Sense of touch 
  • cause of movement 
  • origin of the nerves 
  • transit of the animal powers 

 

REPRODUCTIVE POWER 

The frog retains life for some hours when the head the heart and all the intestines have been taken away. And if you prick the said cord it instantly twitches and dies. 

All the nerves of the animals derive from here: when this is pricked it instantly dies. Quaderni v 21 r. 

[Experimental investigation of the spinal cord of frog] 

The frog instantly dies when the spinal cord is pierced; and previous to this it lived without head without heart or any bowels or intestines or skin; and here therefore it would seem lies the foundation of movement and life. 

Hand of monkey [drawing] 


[Drawing] In this manner originate the nerves of movement above . . . knot of the spine. [Drawing] Whichever of these is pricked is lost in the frog. Quaderni v 21 v 
 

 

Where there is life there is heat; where there is vital heat there is movement of the watery humours. c.a. 80 r. b 

The common sense is that which judges the things given to it by the other senses. 

[The common sense is set in motion by the things given to it by the five senses] 

 

And these senses are moved by the objects, and these objects send their images to the five senses by which they are transferred to the organ of perception (imprensiva) and from this to the common sense; and from thence being judged they are transmitted to the memory, in which according to their potency they are retained more or less distinctly. 

[The five senses are these: seeing, hearing, touch, taste, smell] 

The ancient speculators have concluded that that faculty of judgment which is given to man is caused by an instrument with which the other five are connected by means of the organ of perception (imprensiva), and to this instrument they have applied the name common sense, and they say that this sense is in the centre. And this name common sense they use simply because it is the common judge of the other B.YC senses, namely seeing, hearing, touch, taste and smell. The common sense is set in movement by means of the organ of perception (imprensiva) which is situated in the centre between it and the senses. The organ of perception acts by means of the images of the things presented to it by the superficial instruments, that is the senses, which are placed in the middle between the external things and the organ of perception; and the senses act in the same way through the medium of objects. 

The images of the surrounding things are transmitted to the senses, and the senses transmit them to the organ of perception, and the organ of perception transmits them to the common sense, and by it they are imprinted on the memory, and are retained there more or less distinctly according to the importance or power of the thing given. That sense functions most swiftly which is nearest to the organ of perception; this is the eye, the chief and leader of the others; of this only we will treat and leave the others in order not to lengthen out our material. 

 

 

Experience tells us that the eye has cognisance of ten different qualities of objects; to wit, light and darkness — one serving to reveal the
other nine, the other to conceal them — colour and substance, form and position, distance and nearness, movement and rest. c.a. 90 r. b 

OF THE GROWTH OF MAN 

A man at three years will have reached the half of his height. 
A woman of the same size as a man will weigh less than he does. 
A dead woman lies face downwards in water, a man the opposite way. c.a. 119 v. a 

How radiating lines carry visual potency with them as far as the striking point: 

This our mind or common sense which the philosophers affirm makes its dwelling in the centre of the head keeps its spiritual members at a great distance away from itself, and this is clearly seen in the lines of the visual rays which after terminating in an object transmit immediately to their cause the characteristics of the form of their breaking. 

Also — in the sense of touch which derives from the common sense — does not one see it extending itself with its power as far as the tips of the fingers, for as soon as these points have touched the object the sense is immediately made aware of whether it is hot or cold or hard or soft or pointed or smooth. c.a. 270 v. b 

 

OF THE GAIT OF MAN 

The gait of man is always after the manner of the universal gait of four-footed animals; seeing that as these move their feet crosswise, as a horse does when it trots, so a man moves his four limbs crosswise, that is if he thrusts the right foot forward as he walks he thrusts the left arm forward with it, and so it always continues. c.a. 297 r. b 

Men born in hot countries love the night because it makes them cool, and they hate the sunlight because it causes them to grow hot again; and for this reason they are of the colour of the night, that is black; and in the cold countries everything is the opposite. c.a. 393 v. a 

That cause which moves the water through its springs against the natural course of its gravity is like that which moves the humours in all the shapes of animated bodies. c.a. 396 r. a 

The potencies are four: memory and intellect appetite and concupiscence. 

The two first are of the reason the others of the senses. 

Of the five senses, seeing, hearing, smelling may be partially withheld — touch and taste, not. 

The sense of smell leads that of taste with it, in the dog and other greedy animals. Tr. 12 a 

 

 

All the spiritual powers, in proportion as they are farther away from their primary or secondary cause, occupy more space and become of less potency. Tr. 18 a 

As to the bendings of the joints and in what manner the flesh grows on them in their folds and extensions. Of this most important study make a separate treatise in the 'Description of the movements of animals with four feet', among which is man who also in infancy goes on four feet. e 16 r. 

When a man is walking he carries his head in advance of his feet. When a man in walking traverses a level expanse he bends forward at first and then bends as far backward. f 83 r. 

It is impossible to breathe through the nose and through the mouth at the same time. The proof of this is seen when anyone breathes with the mouth open taking the air in through the mouth and giving it out through the nose, for then one always hears the sound of the gate set near to the uvula when it opens and shuts. g 96 v. 

Dead bodies when male float in water on their backs, when female face downwards. h 31 v. 

If when going up a staircase you rest your hands upon your knees all the strain which comes upon the arms is so much taken away from the tendons below the knees. h 75 [27] r. 

We make our life by the death of others. 

In dead matter there remains insensate life, which, on being united to the stomachs of living things, resumes a life of the senses and the 
intellect.

H 89 [41 J v. 

Every body is composed of those members and humours which are necessary for its support; which necessity is well known and provided for it by the soul, which has chosen such shape of body for a time as its habitation. Consider the fish, which on account of the continuous friction that of necessity it makes with the water, from its own life being a daughter of nature, it is prepared to be delivered, by reason of the porosity that is 
found to exist between the joints of the scales, of a certain slimy discharge, which with difficulty becomes separated from this fish and performs that function towards the fish that pitch does to the ship. Forster m 38 r. 

If you draw in breath by the nose and send it out by the mouth you will hear the sound made by the partition, that is the membrane in . . . 

Fogli a 3 r.