No third ventricle is described by Rhazes or Haly Abbas,[208] but
Avicenna, in his _Canon_, makes an effort to combine the views of
Aristotle and Galen. Speaking of the anatomy of the heart (lib. iii,
fen. xi, chap. 1) he describes the ventricular portion as follows:
‘In the heart are three cavities, two large, and a third as it were
central in position. So that the heart has [_a_] a receptacle [the
right ventricle] for the nutriment with which it nourishes itself--this
nutriment is thick and firm like the substance of the heart; [_b_] a
place where the pneuma is formed [the left ventricle], being engendered
of the subtil blood; and [_c_], thirdly, a canal between the two.’[209]
A somewhat similar account is given in Constantine’s translation of
Isaac.[210] The idea soon crept into European medicine, for in a Pisan
MS. dating from the first half of the thirteenth century[211] a crude
figure of a three-chambered heart is to be found (Fig. 21).
The first translator of the _Canon of Avicenna_, Gerard of Cremona,
whose work appeared towards the end of the twelfth century, improved
on his original. ‘In it [the heart] are three ventricles; two are
large, and the third as it were between, which Galen called the fovea
or non-ventricular meatus, so that there may be a receptaculum for the
thick and strong nourishment, like to the substance of the heart, with
which it is nourished, and also a storehouse for the pneuma (spiritus)
generated in it from the subtil blood. And between the two are channels
or meatuses.’[212] Henri de Mondeville (died about 1320), by going
direct to Galen, avoided some of the errors of Avicenna, with whom,
however, he still describes three ventricles.[213] Mondino does little
but copy the Arabian, whom Manfredi also follows.
We may terminate our description of the mythical third ventricle by
quoting from Bartholomew the Englishman. His encyclopaedia written
about 1260 was translated into English in 1397, and printed by Thomas
Berthelet[214] in the 27th year of the reign of Henry VIII (1535), when
Bartholomew’s work was still extremely popular. Berthelet’s rendering
runs as follows:
‘And the hert hath ij holownesses, one in the left syde, that
cometh sharpe: and one in the ryght side, that is within: And these
two holownesses ben called the wombes of the hart. And betwene
these two wombes is one hole, that some men call a veyne, other
an holowe way. And this hole is brode afore the ryghte syde, and
streyte afore the left syde. And that is nedefulle to make the
bloode subtyll, that commeth from the ryght wombe to the lefte,
and so the spirite of lyfe may be bredde the easelyer in the lefte
wombe.’
In order to understand why all these authors invoked the existence of
the third ventricle, regarded by some of them as a passage between
the other two, we must turn to the physiological beliefs of the age.
It must be recalled that before the demonstration of the circulatory
movement of the blood a certain amount of communication was believed
to exist between right and left ventricles. The complicated nature
of the ventricular cavities and the intricacy of the columnae
carneae promoted the idea of the presence of minute passages in the
interventricular septum. Even so astute an observer as Leonardo da
Vinci considered that ‘the ventricles are separated by a _porous_ wall,
through which the blood of the right ventricle penetrates into the left
ventricle, and when the right ventricle shuts, the left opens and draws
in the blood which the right one gives forth’ (Plate XXXVIII_b_).[215]
[Illustration: Fig. 22. From Johannes Adelphus, _Mundini de omnibus
humani corporis interioribus menbris Anathomia_, Strassburg, 1513. The
diagram shows the two lateral ventricles and the ‘central’ ventricle.
By a printer’s error the letters _c_ and _d_ are transposed. The
_arteria adorti_ is the aorta, the _arteria venalis_ the pulmonary
vein, the _vena chilis_ the vena cava, and the _vena arterialis_ the
pulmonary artery. The auricles are ignored, as is frequently the case
in works of the period, and the pulmonary veins are represented as
opening directly into the ventricles.]
Although the third ventricle is described in all the twenty-five
editions of Mondino, many of which are illustrated, they present no
drawing of it except the wretched little diagram of J. A. Muelich
(Johannes Adelphus) in 1513, which we here reproduce (Fig. 22). The
confusion, however, to which the idea of a third ventricle gave rise
influenced anatomy almost as late as the seventeenth century, and is
illustrated in the anatomical figures of a late edition of Hans von
Gersdorff (1556),[216] where the trachea is actually shown opening into
the left ventricle (Fig. 23). It was Vesalius who took the first great
step towards the discovery of the circulation of the blood, by firmly
maintaining that the interventricular septum was solid and contained
neither passages nor intermediate ventricle.[217]
[Illustration: Fig. 23. From Hans von Gersdorff, _Feldt und Stattbüch
bewerter Wundartznei_, Frankfurt, 1556. The trachea (_d_) is
represented as opening directly into the heart.]