"The negatio formalis is a denial or refusal to communicate this image to the sensorium. In the process of transformation into sensation, the positive ratio is not changed, but remains the same, and is the first part, or basis, both of internal and external sensation.
"The negatio formalis is destroyed or abolished in any case of impression communicated to the sensorium. Natural perception, in its ratio positiva, is not abolished or degraded by being converted into sensation, but is rather exalted, or gifted with a more dignified nature. By as much as public or general knowledge is preferable to private, or public advantage to that of an individual, by so much is sensation preferable to natural perception. Hence nature formed so many organs of sense, that the phantasy might have notice of what ought to be done, desired, or avoided."
He does not doubt that external sensibility is inherent in the nervous parts of the external organ, whence he infers that it may readily incite the fibres of such organ ad appetendum et movendum; for, as external sensation is communicated to the brain by means of the nerves, it must of necessity be true, that these nerves and nervous parts (such as the fibres,) are the subjects of it. Since then sensibility causes its subject to feel, it consequently enables it to desire and move comformably. For perception in any subject is vain, unless it can desire, and appetence is useless, unless it can move. External sensibility, therefore, may be said to render the fibres actu irritabiles, for example, as often as the irritating cause is perceived; but as the irritation is perceived, not by a sensibility, but by a mere natural perception, this it is which constitutes their irritability.
Thus we may perceive that the triunit consisting of perception, appetence, and motion, constitutes the celebrated irritability of our author. But he has been too latitudinarian in his application of the theory; for he did not limit it, as Haller has subsequently done, to one sort of fibres, or indeed to fibres alone, for he says in cap. IX., "It is to be remarked that natural perception belongs to other parts of the body besides fibres; to wit, to the parenchymata, bones, marrow, fat, blood, recrementitious juices, humours of the eye, and such like, all which are irritable, and increase the irritable constitution of the parts, but these parts hardly admit of the existence of animal perception." Haller blames Glisson for having gone so far in his application of the theory, and it is well known that he himself restrained it to the single tissue of muscular fibres, and denominated it vis insitum, or inherent force; whereby he distinguished it from his vis mortua or elastic contraction, on the one hand, and the vis nervosum or voluntary power, on the other; the former being something less, and the latter something more than irritability. Glisson's theory, when fully explained, which we cannot for want of space do here, will be found to bear a very strong resemblance, in many points, to that of Bichat, who has invested the matters of the body with vital powers, far beyond those attributed by Haller; and as we are not furnished in the present article with sufficient space, we hope in some subsequent number, to place this matter in a plainer light before our readers. In the mean time we may remark, that Glisson seems to be the first of those who have placed the subject fairly before the medical public; for although faint traces of a similar theory may be perceived before him, especially by translating terms into their equivalents, yet he has the merit of using a term which, in spite of all subsequent modifications, is in daily use.
Glisson's latitudinarianism may be contrasted with Haller's rigid application: for the latter says, "I call that an irritable part of the human body, which on being touched by a foreign body, renders itself shorter;" thus while Glisson attributes his triunit of perception, appetence, and motion to all the tissues and fluids, Haller confines it to muscular fibre alone. No one can doubt that the membranes of the body are endowed with vital properties, but yet they do not shorten themselves on being touched by a foreign body. Bichat has distinguished their vitality as organic vitality, and the contractile qualities displayed are divided into insensible organic contractility, and into contractility of tissue: but these sorts of contractility mount up by insensible gradations. He says, that "entre la contractilité obscure mais réelle, necessaire a la nutrition des ongles, des poils, &c. et celle que nous presentent les mouvements des intestins, de l'estomac, &c. il est des nuances infinies, qui servent de transition: tels sont les mouvements du dartos, des arteres, de certaines parties de l'organ cutané," &c. We will close with a comparison between Glisson's irritability, and Bichat's contractility. At page 70 of the Treatise sur la Vie & la Mort, Bichat supposes that a "muscle enters into action, 1st. by the influence of the nerves which it receives from the brain, and this is a case of contractile animale," (which differs in no respect from perception regulated by animal appetency of Glisson). 2ndly. According to Bichat, the muscle enters into action "by the excitation of a chemical or physical stimulant applied to it, and which artificially determines a movement of the whole muscle, analogous to what is natural to the heart, and other involuntary muscles. This is sensible organic contractility or irritability," and corresponds to the sensitive perception of the old English physiologist. In the 3d place it enters into action by the stimulus of the fluids which circulate in it, and this is insensible organic contractility or tonicity of Bichat, and is nothing different from Glisson's natural perception. Bichat makes a fourth case; as for example, when a muscle is divided across, it contracts by a contractilité de tissue, or par defaut d'extension. We do not perceive how Glisson's natural perception can be applied to this case, but he treats of it in his fifth chapter under the head of Cessatio: it is that state to which a fibre is reduced when left to itself, and freed from all stimulus.
Bichat has attributed to some fibres the power of active elongation. On this subject Glisson says, "Impossible enim est, ut simplex fibra, sua sola actione, se secundum longitudinem distendat, nec modus quo hæc fiat concipi nedum effari queat non negavero quin in distensione hac, aliqualis fibræ actio includatur, sed ea tota contractiva est, & distensioni ab extranea causa factæ reluctatur." A doctrine as sound as that of the 47th proposition; a doctrine too, without admitting which, we think no man can understand the theory either of simple inflammation, or of the febrile affections. We hope to resume this subject at an early period.
FOOTNOTES:
[25] Hæc ei generatim videbantur, ex igne omnia constare eodemque interire. Diogenes Laertius.
[26] Quatuor æternus genitalia corpora mundus
Continet; ex illis duo sunt onerosa, suoque
Pondere in inferius, tellus atque unda, feruntur,
Et totidem gravitate carent, nulloque premente
Alta petunt, aer atque aere purior ignis.—Ovid—Metamorph.
[27] Lib. de Carnibus, Hippocrates says: Quod Calidum vocamus, id mihi immortale esse videtur, cunctaque intelligere, videre et audire, sentireque omnia, tum præsentia tum futura: cujus pars maxima cum omnia perturbata essent in supremum ambitum secessit; quod, mihi veteres æthera appellasse videntur. Altera pars locum infimum sortita, terra quidem appellatur, frigida et sicca multas que motiones habens, et in qua multum sane calidi inest. Tertia vero pars medium aeris locum nacta est, calidum quid existens. Quarta pars terræ proximum locum obtinens humidissima et crassissima. His igitur in orbem agitatis cum turbata essent, calidi magna pars alias in terra relicta est, partim quidem magna, partim vero minor, alias etiam valde parva, sed in multas partes divisa. Et temporis successu a calido resiccata est terra, ista in ea tanquam in membranis contenta circumse putredines excitant, ac longo tempore incalescens quod quidem ea terræ putredine pinguedinem sortitum est et minimum humidi habet, id citissime exustum ossa produxit. Quæ vero naturam glutinosiorem sortita sunt et frigidi communionem habent, ea neque calefacta exuri potuerunt, neque etiam humida fieri ideo formam longe ab aliis diversam nacta sunt et nervi solidi exciterint, cum non multum in iis frigidi inesset. At venæ frigidi multum habebant cajus pars circumcirca ambiens et quod erat glutinosissimum, a calido exassatum membrana extitit. Quod vero erat frigidum, a calido superatum, dissolutum est ideoque humidum evasit.