The only physical condition of nerve itself apparent in these derangements, is augmented arterial action in the nerve structure; but this is involved in some obscurity. The phenomena of nerve action during irritation and excitement, probably depends upon the rapidity of progression of nerve force, just as the amount of electrical fluid transmitted along a conducting wire from ten four-inch voltaic pairs in series, is considerably greater than the amount transmitted from two pairs of the same magnitude, depending not upon the extent of surface, but upon the reciprocal action of the series.

In corroboration of this, there is, I believe, in all cases of nerve irritation and excitement, an increased rapidity in the respiratory functions, the source of this force.

Irritation and pain cannot long continue in the nervous structure without producing determination of blood to the part; and hence the old axiom, 'ubi stimulus, ibi fluxus.' When an increased flow of blood to any part of the nervous system takes place, and continues to progress, there are invariably observed to occur three distinct stages of morbid action: 1st, Excitement; 2ndly, Irritation; and lastly, Oppressed action; one stage or the other obtaining just in proportion to the degree of arterial action prevailing.

Increased arterial action itself appears to augment, to some extent, the natural susceptibility and irritability of the neural structure. Although we have already seen that nerve irritation is a condition independent of the blood, there is little doubt that this state (including the structure of the great centres) is attributable sometimes to the circulation of impure or irritating sanguineous fluid, or to the contact of morbid or irritating secretions with the nerve fibre; all which conditions of blood and secretions originate in the state of the nervous ganglia, which supply the digestive and secernent

organs.

The nature of the blood which has to supply the nervous system with nutriment for its development, integrity, and the continuance of its vitality, formed

as it is under the influence, and subject to the entire control, of the nervous centres, may be such as to materially alter the integrity of its organization, and disturb its conducting powers; and either by the deposition of tubercles, etc. in the nerve structure, or by its irritating qualities, may become itself a direct source of irritation, and yet can only be looked upon, like the mind as an external irritant upon nerve, the great agent of the frame.

It will thus be seen what an incalculable influence the quality of the blood possesses in cases of mania and other mental diseases.

It is evident that the congestion and effects thus produced in the nerves, as they are by increased action of the circulatory system, are widely different in their characters and treatment from the congestion which arises from obstruction to the return of the blood by the venous system; in all which cases nerve depression, and loss of excitability, invariably prevails.

The condition of nerve which takes place in cases of terrible injury, crushes, lightning, etc. is no doubt, in some instances, the complete destruction of the nerve structure itself, and of its capability for conduction. In other instances, it is probably the instantaneous withdrawal of the whole powers of the system towards the injury, or in other words, the direction of all the nerve force of the frame towards the seat of the lesion; and, at other times, the momentary annihilation of the powers of life altogether, which latter appears to be the commonly received opinion. Professor Matteuci proved, in several instances, that in the frog all the powers of life were instantly destroyed by a sudden crush of an extremity, or some large portion of the frame.

Diminished

excitability is produced by the same causes, but is generally a secondary effect of those causes -a result of augmented sensibility, and very frequently alternates with the latter. Indeed, a general law in the animal economy is, that a corresponding depression is, at all times, the result of over-excitement.

Nerve exhaustion is only a still lower degree of diminished excitability, or loss of nerve force; being the product of more powerful or long continued irritants, morbid influences, shock, extreme violence, excitement, etc.

In nerve exhaustion, the development of nerve force, as well as its transmission through the nervous filaments, is probably considerably diminished.

The respiratory functions are very slowly or inefficiently performed, evincing a very sparing development of vital energy; the pulse is greatly diminished in frequency or power, and evinces, when attended with loss of consciousness, etc. a complete failure in the vital powers.

Complete loss of nerve function is the zero of the same condition, arising from the destruction of excitability in the nervous system by the influence of the imponderable forces, sudden shock, intense lesion, the poisons, and, in some instances, the result of injury producing destruction of these organs by sanguineous and serous effusion, ramollissement or softening, and of tumour, and other morbid growths, etc. Other instances arise from vascular fulness and congestion, and are referrible to the condition described as nerve irritation, attended with that morbid condition.

It appears, therefore, that the condition of nerve irritation is wisely and beautifully ordained by the great Creator and Preserver of our species, for the very purpose of exciting increased action, in order to the ejectment of all noxious matter and influences which have insidiously introduced themselves into the frame, in spite of all the admirable provisions for their exclusion.

Like the detective orifices of the body for external irritants, the very basis of the frame (for I most assuredly look upon nerve structure as its basis), the great centres of the nervous system, themselves form an instinctive, conscious, and almost intelligent apparatus for the detection of noxious material existing in the various liquids and tubes, vessels, and cells, and secretory apparatuses of the body-in fact, naked and unconcealed poison in every cavity or interstice in the

animal economy; and immediately on its discovery, they set to work the various vascular forces of the muscular or system, or the excretory functions, for its expulsion.

As a further proof of the neural basis of diseases, I have extracted and compared their various stated and admitted causes; and find them to be, in most instances, such as would induce affections of the nervous system, analogical with the conditions already noticed. They are chiefly as follows:

CLASS I.-EXCITING CAUSES.

1. Cold or wet; sudden alternations of temperature; applications of cold to the heated body, or of the body much heated to ordinary temperatures; sudden chills produced by cold air, etc.; excessive heat, exposure to the sun's rays, etc.

2. Violent exercise, local and general fatigue, etc.

3. Intemperance.

functions, as tight lacing, etc. 4. Suppressed evacuations; obstructed

5. Repulsed eruptions.

6. Passions of the mind, anger, fright, horror.

7. Contagion; irritants, as poisons; excessive irritation, as the shock of parturition; of morbid matter; irritation in the intestinal canal; acrid matter in the primæ viæ; mechanical and chemical irritants and injuries, etc. etc.; teething, worms, etc.; to which may be added spiculæ of bone, adventitious growths, etc.

CLASS II. PREDISPOSING CAUSES.

1st.-To Inflammatory Diseases :1. Plethoric habit.

2. Strong muscular system. 3. Indulgence at table. 4. Good unimpaired constitution. 5. Suppressed evacuations. 2nd.-To Nervous Diseases :

1. Weak and delicate habit. 2. Nervous temperament, and general and local debility.

3. Much sensibility and irritability. 4. Sanguine temperament. 5. Study, excessive grief, anxiety, the passions.

6. Poor living; preceding disease. 7. Indulgence in spirituous liquors.

8. Excess in venery, etc.

9. Profuse evacuations, or their suppression.

10. Warmth of season or climate.

11. Cold and wet seasons-variable temperature.

12. Damp and low situations-marsh miasma, etc., and moist localities, etc.

13. Hereditary taint, scrofula. 14. Want of cleanliness; pure air, ventilation, etc.

15. Childhood, puberty, adolescence, manhood, old age.

We have thus evinced that, of the conditions and influences assigned as the principal causes of all diseases (whatever may be the hypothesis to which the authors cling who have enumerated them) the greater part are such as are commonly received as affecting primarily the nervous system, and that with very few exceptions; and no person, after exposure to some of these causes, can tell what will be the phase of disease manifested.

SIMPLE NERVE IRRITATION.

Irritation of the trunk, branch, or centre of any particular nerve or system of nerves may exist, isolated, as it were, from every other class of nerves, and display its characteristics either in the nervous centre itself, in the branches which communicate with such centre, or in the ultimate fibrilla of such branches; or the effects may be manifested upon the peculiar part, function, or organ which such nerve supplies.

If this irritation exists idiopathically in the brain, there may be cephalalgia (headache), mania, or congestion; irritability or sleeplessness; fretfulness or excitement, or any of the ordinary symptoms of cerebral irritation.

If it exist in the cerebellum, or spinal marrow, there may be spinal pain or congestion; lassitude or weariness; 'spinal irritation' (so denominated); starting in the sleep; hysteria, etc.; with the ordinary effects upon the branches, and the organs which they supply, which derive their origin from this division of the nervous system.

If the irritation exists in the gan

glionic centres, pain may be entirely absent, mischief may rapidly be going forward in some organ or viscus supplied with nerves from this great centre, and yet no symptoms which indicate serious internal lesion may present themselves; but there may, on the contrary, be developed neuralgia, rheumatism, gout, inflammation, cuticular eruption, ulcer, or tumour, etc. in some distant part, far away from the original seat of disease, with occult signs manifested in the organ affected, appreciable only by medical men, highly conversant with morbid phenomena of this class Irritation of the motor and excito-motor nerves, proceeding from the spinal marrow, will produce spasmodic action in the muscles which they supply (see Dr. Marshall Hall's interesting labours); and will be manifested in the form of colic or tetanus, cramps or convulsive movements, or twitchings, startings, epilepsy, cough or asthma, laryngeus stridulus, or pertussis, etc.

Irritation fixed in the branches or nerves of sensation, induces neuralgia, sciatica, tic doloreux, odontalgia, gastrodynia, or pain in the nerve fibre of any locality supplied by these nerves, and from whatsoever source arising.

Irritation in the cuticular organic nerves locks up perspiration, or produces augmented diaphoresis, or these conditions alternately occurring in the nerves which supply the mucous membranes, arrests their secretions, producing a dry and parched condition of these surfaces, such as occurs in fevers, especially of the typhoid kind, or in the obstinate constipation which takes place during intestinal inflammation; or it stimulates the membranes to exudation, and pours out mucous, lymph, purulent matter, or even blood.

Irritation of the nerves which minister to the various secretory organs of the body, as of the kidneys, liver, uterus, mamma, etc. etc. in like manner, either induces an increased flow of vitiated secretion, or arrests the functions of the organ which they supply.

(To be continued.)

THE

RIGHT

FRUITS.

5. Decay, or Putrefaction.-The decay of fruits might have been considered under the head of Diseased Fruits, since such decay may, and probably will, have a visible effect on the health of those who make use of it. Most persons avoid fruit which is wholly decayed, as it were instinctively; except in making cider. In the latter case, many farmers consider a few decayed apples as quite harmless; and some think them even useful.

It does not, however, seem to be considered that fruit is injurious when in a state of partial decay only. Many, very many, seem to think that after the de. cayed part of an apple is removed, the remainder is just as wholesome as ever. They would not, in all probability, like the flesh of an animal, killed while it had a mortified limb or organ, even after the mortified part had been cut away. There would probably be a suspicion that the rest of the animal was more or less affected. It is true, that the interior of the apple is not exactly like that of the animal; but does any one believe that there is no change in the parts of an apple contiguous to a decayed or putrid portion? If so, he is much mistaken.

More than even this, however. There is a degree of decay in all fruits before it is readily discoverable by the eye. In the rich juicy summer fruits, this is sometimes quite obvious to the smell, and it is often so to the touch. Fruit, in a decayed or decaying state, we repeat it, can never be as wholesome as before; and should, if practicable, be avoided.

6. Proper Hours.-Fruit is not so very easy of digestion as many seem to suppose. The mistake has arisen from the fact, that an over-quantity of it does not seem to be very mischievous. This, however, is not owing to its digestibility, but to its want of stimulation. It is also supposed, too, that fruit digests easily, because children are very fond of it, and do not often seem to suffer

from the use of it. They do, however, suffer from it, much oftener than has usually been supposed; as may perhaps be inferred from what we have already said elsewhere. One thing, however, in regard to children should be remembered; that, if their digestive organs are not quite so strong as those of adults, they are at least more active, much more so; which makes up, in part, for their want of strength. Were it not so, they would suffer much more from their excessive use of fruit than they now do.

We have said that fruits are not very easy of digestion. They are, however, easier in proportion to their perfection. This might have been urged as a reason why they should be of good quality, seasonable, healthy, etc. But with every thing else, and all circumstances favourable, they can be digested with tolerable

ease.

One favourable circumstance is, full bodily vigour. On this account, fruits should generally be used in the early part of the day, and seldom late in the evening. The morning is, on the whole, best; and next to that, perhaps, the middle of the day. The worst hour, is the hour just before going to bed.

7. State of the System.-On this topic a great deal might be said which would be to little purpose, unless our readers understood better the laws of the human economy. We can only glance at a few of the plainer points.

The drier fruits are adapted to the cooler, drier weather; the moister ones to the hotter. Thus the less juicy sorts of cherries, pears, and peaches, are not only most grateful but most salutary, when the weather is not excessively hot; while the currant, and the melon, and the moist peach, are best adapted to the hottest days.

The same may be said of the different hours of the day. If fruits are eaten at all late in the day, especially after the middle, it should be the more watery, as the melon.

Again the sweeter kinds are, as a general fact, best adapted to the cool or moderately hot hours and days; and the gently acid sorts to sultry weather.

Again, still: if we use at all those which are more difficult of digestion, they should be used when not only our system in general, but especially our digestive organs, are the strongest; as in the morning, or when we have not been recently unwell, or over-heated, or over-fed, or fed with too nutritious or too stimulating aliment.

Once more. Fruits are best adapted to our wants, and will best agree, in exact proportion to the perfection of our health. Thus when people tell us, as some do, that fruit does not agree with them, we conclude, almost at once, that their systems are out of order. They may not perceive it; but there is trouble somewhere, amounting at the best to incipient disease.

The foregoing view of the case, though affording nothing more than a few brief hints on the subject, will be confirmed by considering the arrangements of Divine Providence.

Thus, as

a general rule, the fruits which come first, and those which come last in the season, when the weather is usually less hot and dry, are not so juicy as the currant, the blackberry, the watermelon, the musk-melon, which come during the more sultry season. There may be apparent exceptions to this rule; but they are not numerous. But on this part of our subject we cannot enlarge.

8. Quantity. Most adult persons fall into the error of eating fruits but rarely, and then eating them in too large quantity. Children, it is true, are not only ready to eat them too often, but in too great quantity also. It seems desirable that they should be used in very moderate quantity only, both by children and adults; but they should be used, for five or six months in a year, almost or quite every day.

Some will inquire what the specific quantity eaten should be. This it is as impossible to determine as it would be to say how much oxygen a person ought to breathe in a day, or how much shoe leather he ought to wear out in walking.

Some hints may, however, be derived from our remarks under the two or three remaining heads of our subject.

Simplicity. The simplicity of fruits has been much overlooked. There are, indeed, some combinations with other substances, and some changes of the fruit itself, which are less hurtful than others; nay, which, in particular states of the system, may be, and undoubtedly are, salutary. Thus, the good mellow ripe pear or apple, though best in its natural state, may be most salutary, if used at all, in particular states of the system, when boiled, baked, or roasted. It may, indeed, be a question, whether, in these circumstances, fruit is the best thing for us; but this question we cannot, at present, settle.

But what we object to is, not the occasional baking of an apple or a pear, but that perpetual din of cookery and change which prevails, of our simplest fruits. Thus they must be sugared, or spiced, or made into pies or puddings; or they must be eaten with wine, or milk, or made into preserves or sweetmeats. Now this is all folly, and worse than folly, to the healthy. It is not only an absolute loss of gustatory enjoyment, but of health; provided, we still say, we have health to begin with. As for the sick, we repeat it-we are not here writing for them, but for the healthy.

We have said that the practices to which we allude, are not only foolish, but unhealthy. We will say more, still; they are wicked, or would be so, did people understand the matter just as it is. By what right do we waste valuable time in those kinds of cookery, whether it be of fruit or anything else, which neither make the substances upon which we operate, any more agreeable to the healthy appetite, or to any individual in the wide world any better? Is it not the legitimate object of Christian cookery to make food more palatable, more nutritious, more abundant, or more wholesome? And is not that time which is spent in cooking without accomplishing any of these objects, wickedly wasted? But none of these objects are accomplished in the case we have just named, except the first; nor