The objections to the supply of blood, and consequently, (according to the Zoonomia,) of oxygen, to the fœtus, are likewise inconclusive. On this hypothesis, (says Mr. B.) much must be done, in the short space of a few hours. New blood vessels are formed into a complete circulatory system: they are drawn to the sides of the uterus: and the motions of the fluid in which they float, cannot prevent them from adhering to the vessels of the parent.' If Mr. Brown will refer to the tables of Dr. Hunter, or of Dr. Denman, he will find that much of what he has here stated as an hypothesis is matter of ocular demonstration.-He has objected, with more success, to the formation of a perfect foetus from a simple living filament:-but, indeed, most readers will probably think that he has bestowed unnecessary pains on the examination of an opinion which is confessedly gratuitous.-His remarks on the still bolder hypothesis advanced in the Zoonomia, which derives all living bodies from a similar source, we shall give in his own words: The various species of animal, and vegetable life, Dr. Darwin believes to have proceeded, from a single living filament, susceptible of modification, by the accretion of parts, and by its own exertions. The This opinion may, perhaps, surprise us into momentary assent, by its boldness, and the wonderful simplicity, which it seems to introduce; but, if we demand evidence, we obtain only a few loose analogies, which do not favour the supposition. Degrees of qualitics, as of strength, and swiftness, in the horse, may, as Dr. Darwin contends, be in some measure hereditary; but no new quality is su perinduced, and, therefore, the species continues the same. winged butterfly, it will also be granted, bears little resemblance to the creeping caterpillar, or the respiring frog to the subnatant tadpole; but the wings, and the lungs are not communicated to their posterity. The butterfly, and the frog produce again the caterpillar, and the tadpole; and thus, instead of continued improvement, a circle of changes takes place. The supposed original filament must have required nutriment, for its growth: yet no animal, nor vegetable matter, was in exist ence; so that, instead of giving rise to the various system of life, it must have perished, or continued to exist, unexpanded, and alone. But, admitting it to have been capable of growth, and reproduction, as sexual generation was impossible, in a single individual, it could multiply itself, only by the accretion of parts. Such a pro geny, it is observed, "are always exact resemblances of their parent,' p. 523. To what, then, if we suppose a single original filament, is the present difference of sex, and of species, to be ascribed? Dr. Darwin seems to consider the animals of former times, as possessing powers, much superior to those of their posterity. They Should not this word be exchanged for circulating? Circulatory, if admitted in English, must refer to quackery. Rev. reasoned : reasoned on their wants: they wished and it was done. The boar, which originally differed little from the other beasts of the forest, first obtained tusks, because he conceived them to be useful weapons, and then, by another process of reasoning, a thick shield-like shoulder, to defend himself from the tusks of his fellows. The stag, in like manner, formed to himself horns, at once sharp, and branched, for the different purposes of offence, and defence. Some animals obtained wings, others fins, and others swiftness of foot; while the vegetables exerted themselves, in inventing various modes of concealing, and defending their seeds, and honey. These are a few of many instances, adduced by Dr. Darwin, which are all objectionable, on his own principles; as they require us to believe the various propensities, to have been the cause, rather than the effect, of the difference of configuration. The fish did not become a subnatant animal, by having received fins; as it must have been an inhabitant of the water, before it could have felt the want of them: and the hog must originally have had propensities, different from those of the sheep, or it would not have wished, nor attempted, the formation of its snout. Of all modes of reasoning, that is the easiest, which contents itself, with simple supposition; but to this species of argument no bounds can be fixed. It will prove, as readily, that a single filament gave rise to the complicated system of the universe, as that it gave rise to all the tribes of animals, and vegetables, that inhabit our earth. If we admit the supposed capacity of producing organs, by the mere feeling of a want, man must have greatly degenerated, or been originally inferior, in power. He may wish for wings, as the other bipeds are supposed to have done with success: but a century of wishes will not render him abler to take flight. It is not, however, to man, that the observation must be confined. No improvements of form have been observed, in the other animals, since the first dawnings of zoology; and we must, therefore, believe them, to have lost the power of production, rather than to have attained all the objects of their desire. If we may be allowed to judge, from their situation, the hare has still, in the chase, the same reason, as the birds of old, to wish for wings, and the dove for greater swiftness of flight, to escape from the pursuing hawk: yet the scale of infe riority still subsists; and such is the order of nature, that the strength of all is supported by the weakness of all.' On the much-disputed subject of Insanity, Mr. B. has advanced his own hypothesis: he supposes it to, depend on peculiarly vivid ideas of imagination. Whether it be strictly philosophical to assume a term merely relative, and applicable to a sound state of mind in many cases, as an exclusive cause of disease, we shall not determine :-but we apprehend, that the various forms of insanity cannot be referred to this, nor to any single cause. Mr. Brown, indeed, has comprehended, under the general term Madness, both the acute and chronic states states of the disease, both mania and melancholy. We should doubt whether he has been accustomed to observe the unhappy. subjects of these disorders; if he had, it would have been impossible for him, acute as he is, to have confounded the distempers.-The maniac often expresses contempt, or hatred,, for those to whom he was most warmly attached during health: but, from a more vivid state of his ideas, we should have expected only an extravagant increase, not a change of affection.-The author seems, indeed, to have felt the insufficiency of this cause, for he admits that patients combine imagination with, their perceptions' in maniacal cases. This expression, though certainly confused and obscure, is worth remarking; because it leads us back to the common doctrine, which constitutes depraved perception as the basis of madness. When the insane person,' says Mr. B. fancies himself a sovereign, he connects ideas of grandeur with every object around him. All is gold, or marble, or purple, or fine linen. His seat is a throne; his chamber, a palace; his keepers, regal guards.' In this case, it is evident that something more than the connection of incongruous ideas is required to explain the phænomenon. There must be a mistake respecting familiar objects; that is, a vitiation of perceptions, in order to give the maniac the impression of gold from an handful of straw, or of purple and fine linen from his blanket. Besides, we know from the accounts of persons who have recovered from maniacal paroxysms, that their perceptions have been much perverted: for patients sometimes recollect, with great accuracy, whatever has impressed their minds during the furious state of insanity. They report that objects have presented a fiery appearance to them; and that their friends have seemed to have assumed figures which excited their horror or disgust.- Mr. Brown is also inaccurate in stating that maniacs are best restrained by terror. This antient doctrine has been happily superseded by the mild and benevolent discipline introduced by Dr. Hunter, in the Asylum of York, and now generally imitated in similar places of confinement. The opinion of our author applies, however, though with some limitation, to the chronic state of insanity: for, in me-. bancholic persons, one or more ideas are felt so acutely, that they divert the mind from its usual operations on others. Yet, in these cases, there is only a partial vivacity of ideas; general impressions become indifferent; and it is sometimes impossible to attract the attention of the patient to the most obvious contradiction of his mistaken opinion. Instead of agreeing with Mr. Brown, therefore, that madness is a disease: of the motives alone,' we would say that mania is a disease of perception, and that melancholy is a disease of motives.... It It may be observed, as a farther objection to Mr. B.'s theory, that paroxysms of furious insanity often occur after hard drinking, and total want of sleep, for several days and nights successively; that is, when, in the language of Mr. B. the excitability of the brain has been exhausted by the most powerful means. It is impossible, according to his principles, that a vivid state of ideas should be produced by such causes; yet the fact frequently presents itself to medical practitioners. Respecting the theory of Fever, we agree with the author in thinking that nothing really satisfactory has yet been advanced. If, indeed, we examine some of the most celebrated opinions concerning the proximate cause of fever, we shall find that they all describe nearly the same fact, in different terms. Boerhaave supposed it to consist in obstruction, from the state of the fluids, to the circulation through the extreme or capillary vessels; Hoffman ascribed it to a spasmodic stricture of those vessels; and Dr. Darwin to a torpor of the heart, arteries, and capillaries. All these theories, however different in appearance, enunciate little more than this fact; that, during the cold fit of fever, there is a suspension of circulation in the extreme or capillary vessels. To account for this state of the vessels, is the great desideratum of pathology; and we have to lament that ingenuity has hitherto been baffled in attempting to supply it. The accumulation of sensorial power, which Dr. Darwin supposes to take place during this state, is shewn by Mr. Brown to be inconsistent with his previous hypothesis of the nature of that supposed fluid. The accumulation, which occasions the increased action, takes place, during the cold fit; and the cold fit is said to be induced, in two modes, by the diminution of stimulus, or by the diminution of sensorial power. Let us consider the possibility of accumualtion, in each of these states. In the former, a stimulus, of less force, is applied to the natural quantity of sensorial power; and no accumulation can take place, unless it act on a less quantity, than the usual stimulus. If it act on a less quantity, it is evident, that the sensorial power might be diminished, without a diminution of effect, in direct opposition to the laws of animal exertion. Even if it were not in opposition to laws, previously inferred, it would be difficult, to conceive, in what manner, a portion of sensorial power, which would have been expended by a more powerful stimulus, remains unaffected, when a gentler is applied. The whole is affected, in a certain manner; and the whole, or none, must, therefore, be expended. When the usual stimulus acts on diminished sensorial power, it is evident, that no accumulation can take place, if the supply from the brain continue to be expended, in the same manner, as during the sound state of the organ; and this expenditure must continue, unless unless the stimulus have lost its power, or the spirit of animation its excitability. Even if we suppose the quantity of sensorial power, expended, to be always proportional to the force of the stimulus, without relation to the strength of the organ, accumulation will, indeed, be possible, but the hot fit of fever cannot be induced: for the usual stimulus, whatever be the state of plenitude of the organ, will excite its precise quantity of sensorial power; and thus the motion of the capillaries, and heart, and arteries, will not be increased.' The author considers the class of Sensitive Fever, also, as irreconcileable with the principles of the Zoonomia: but, having already occupied so large a portion of our Review with extracts from this work, we cannot admit farther quotations. To conclude, we think that this book is a very respectable specimen of the author's talents and attainments. With much vigour and acuteness of mind, it exhibits a liberal and truly philosophical spirit; and though we have ventured, in some instances, to express a difference of opinion with Mr. Brown, we cannot take leave of his performance without intimating our hope that we shall have fresh occasions, hereafter, of giving our unbiassed suffrage to his abilities. ART. IV. Essay on the Causes, carly Signs, and Prevention of Pul s this essay is intended for popular instruction, the author Dr. Beddoes thus controverts the opinion entertained by many persons, that there is little suffering in consumption: The short teazing cough at first, provoked by incessant tickling in the throat, as if the minute fragment of some extraneous body had immoveably fixed itself there; the subsequent hard rending cough, attended sometimes by retching and vomiting, sometimes by stitches which necessitate the most violent struggle against the continued solicitation to cough, and severely punish a moment of inattention; the expectoration sometimes nauseous, always offensive to the eye, tient and harrassing when it is not free; the languor with which the pa REV. JULY, 1799. U Fer...r. |