traction and hardening of the penis, is more observable in animals of the genus Equus. The vascular system is composed of gelatin, excepting the larger arteries, in which fibrine appears under a peculiar modification. Can any thing be more contractile than these sanguineous capillaries, which return upon themselves almost immediately after having been distended by the influx of fluids? than all those excretories which ejaculate their fluids, such as the salival capillaries, the lachymal, &c. ? all the excretory ducts do not, like these, spirt out their fluids, but all of them have force enough to drive out their contents and conduct them toward the place of their destination. It cannot be said that this is not a shortening of their fibres; for it is so, to that degree, that most of these canals close of themselves, and become obliterated when they cease to act.

But are not we now speaking of that vascular apparatus destined to the purposes either of the blood, the lymph, or the secreted fluids which constitutes the greater part of the viscera? It will therefore be useless to dwell on the proof, that contractility, shortening, and condensation of substance, takes place in these organs, and determines the movement of the fluid columns that pass through them.

It is by nervous influence, innervation, that all these vascular movements are excited, sustained, and accumulated. Experience permits no doubt on this subject, since every thing which excites the nerves of a vascular apparatus, every thing which exalts its sensibility, calls to it the fluids in greater quantity, and determines either their accumulation or their rejection in more than the usual proportion, or their different transformations and combinations. Stimulation then, reaches the vascular fibres formed of gelatine essentially contractile, as it does the fibrine of the muscular fibre. It produces in them, in like manner, condensation followed by elongation and relaxation. The relations and the alternations of these two movements, explains all the displacements of the columns or masses of fluid which circulate in all directions across our organs. Why do they not say that the nerves are the sole agents in all these phenomena, and that the movement of condensation of a vein or a lymphatic which diminishes the caliber of the containing vessel to suit the size of the column of fluid, is a nervous phenomenon with which gelatin has nothing to do? This would be just as reasonable as to say that the muscular fibres are passive when the muscles contract !

Gelatin, moreover, forms ligaments, cartilages, and bones. This animal matter has not lost its contractility in these organs, for that property is essential to it; but its effects are something entrammelled by the crossing and decussations of the gelatinous fibres, and sometimes by their combination with inert matter, as phosphate of lime, which gives solidity to the bone. It is in this manner that Gelatin is prepared to answer the purpose of support to the organs, and determine the form and attitude of the animal.

men.

We come now to the third form of animal matter AlbuWe had better study it in the brain, for it is there in considerable mass, and the eye can decide upon its motions. But the motion producing condensation is manifest beyond dispute, when the upper part of the scull is removed. After every pulsation of the heart, and after every inspiration, the brain is seen to retreat upon itself after having been raised up and enlarged. The condensation takes place in the direction of the white fibres, from the circumference to the centre, and to the base. Moreover, the serous membrane insinuated between the different folds and surfaces of the encephalic matter, admits beyond doubt, that an undulatory motion continually takes place among the fibres, and the encephalic mass is in continual agitation. A man who would doubt this fact, must be devoid of all talent for observation and induction. We have already stated, and we repeat, that these encephalic movements are antecedent to the serous surfaces of the encephalon, and ought to produce them; for two gelatinous surfaces in contact, and at rest, with no intervening motion, would adhere to each other.

Since motions of alternate contraction and relaxation take place in a mass of albuminous matter, it ought to exist in cach fibre in particular; nor can we suppose them strangers to the influence of innervation. No doubt something else takes place in the interior of nervous tissues; but we cannot say how it is connected with these movements, or how it may contribute to innervation. Still, contractility remains as a vital property of the nerves; the envelopes of the encephalon, and the neurilema of the nerves, and the vascular system of the one and of the other, possess contractility as gelatinous tissues. The albuminous nervous fibre possesses this property as Albumen. It is by means

this important substance that wo are connected with oxygen, with caloric, with electricity, and the other

exist, it is in consequence of the laws of vital affinity which has arranged the molecules of which it is composed. The phenomena of composition then, are in the developement of each animal, anterior to the phenomena of excitation: these two phenomena therefore are not the same. This seems to be plain and simple reasoning: how it can be otherwise regarded we know not.

It is not our intention to discuss the first cause of the molecular affinities which organize a living body, but merely to give an idea of the phenomena that relate to excitation in man, considered in his perfect state of organization. We shall therefore proceed to the fundamental positions of the physiological doctrine by some developements on sensibility, and on the part taken by the nervous system in perception and motion. Thus we shall have treated the subject of vital properties, as much as is necessary to understand the phenomena of Irritation, the chief object of this first part of our work.

CHAPTER IV.-ON THE FUNCTIONS OF THE NERVOUS SYS

TEM IN THE PHENOMENA TERMED INSTINCTIVE AND
INTELLECTUAL.

In this chapter I shall examine in three successive sections-1st. The functions of the nervous apparatus in the adult. 2dly. Their gradual developement from the embryo, till the man arrives at his full and perfect growth. 3dly. The reasons of the qualities which distinguish man from other animals.

Sec. 1st.-Functions of the nervous apparatus in the adult. The duties of the nerves considered in this state of full developement, is to propagate stimulation in the animal economy, and to keep up all the functions by continuing them under the agents of excitation. This is proved by experience, independently of any and every system and explanation, as to the mode of receiving and propagating these stimulations. We know also, that the result perceptible to our senses is an augmentation of the phenomena of life, in those parts to which the stimulation is transmitted, as well as in those where it first took place. After these preliminaries, we may proceed at once to discover the functions of the nervous system, which we shall divide into four stages or degrees.

1st. Setting out from the most simple functions of the