Henry Curtis

“ Conclusions have likewise been erroneously drawn from the fact of a limb, dying when the supply of blood is cut off from it, but which circumstance serves to prove that blood is the most natural stimulus, and is essential to the perfect organization of the part; but the blood is nothing without its oxygen. Abstract heat, which is an exciting agent next in power, and you produce a like effect; mortification and death, will ensue; yet no one will pretend to say that the principle of caloric which pervades all matter is life. ”

“ The capacity and aptitude for motion, observable in man, naturally lead us to an enquiry into the general principle of his corporeal functions. To a disquisition of which I devote the following pages.
Aware of the intricacy of my subject, and that the operations of the animal body necessarily embrace agents not within the range of our senses, I cannot indulge in the hope that I shall be altogether successful in an examination of the laws of its economy. Where so many enlightened and able intellects have labored in vain, it would require an excess of vanity in me to expect to succeed ”

“ Much may be argued from the importance of the brain in the economy of the system and the rank it occupies in intellectual operations. And though the mode of connexion between mind and matter, and the living principle and it, be not demonstrable to the senses, and will probably forever remain among the arcana of nature, yet we continually witness their effects and may conceive them a quality impressed under particular circumstances on the nervous system: possibly something in the way that bodies [25] are endowed with the power of affinity or principle of gravity. ”

“ Amidst our contemplation of the various simple and compound actions, of which the human body is capable, and in which it is perpetually engaged, we are unavoidably led to ask—whence is the peculiar power or capacity, so admirably diffused throughout its numerous parts, by which those actions are performed? ”

“ That eggs resist in proportion to their freshness a reduction of temperature, is not in my conception necessarily owing to their vitality; which may be inferred from the circumstance, that as long as they were capable of being hatched, however stale, they must still retain their principle of life, and therefore, a stale egg able to afford a chick by incubation, should freeze no sooner than one newly laid. ”

“ These considerations are, I judge, sufficient to put to rest all idea of an independent organic life: If others are wanted, it may be shewn that life, sense, and self-action, are inconsistent with the general properties of matter. ”

“ That the principle of life or capacity of acting, or being acted on, is strictly the property of one part, and is by diffusion communicated to the rest, we have much reason to conclude from the phenomena of both health and disease. ”

“ There is little doubt that the contractibility of the muscular fibres is variously disposed in different animals and that particular parts may possess more tenacity of action than others; but if it were a constituent principle of the part, it should continue undiminished in power until the texture be entirely destroyed, and not gradually decrease in energy, as is the case, till it cease to act altogether. It may be strongly urged against this hypothesis that stimuli applied to the nerves soon after the death of an animal, produce more violent action than when applied to the muscles themselves ”

“ Soon however the vital energy manifests itself in the formation of red blood, and the motion of a point which being capable of reflecting light presents to the senses marks of distinct organization. Yet from this we derive no evidence that this point is the first to possess life, but only, that it shews itself first, by means of its reflecting powers. And thus though we admit the proposition, it can assist the cause it was adduced to support but little; for the moving energy, we presume may be derived from co-existent parts. ”

“ Others, writers of much reputation and celebrity, have contended for the existence of an innate independent principle of life in the muscles, and the plausible ingenuity with which these opinions were supported, could not fail to procure many advocates, and has indeed enlisted in its cause such a body of respectable talents, as to induce me to hesitate in my intended opposition: Nor do I now venture presumptuously to undertake the settlement, but shall only offer such reasons in objection to the doctrine, as have been suggested by various circumstances. ”

“ Nor must we commit our barque to the full and easy flowing stream of conjecture and hypothesis. Conjectures are ever vague and hypothesis seldom leads to the discovery of truth.
Some physiologists, and those of no mean note, have considered the operations of the human frame as a circle of functions governed by mechanical organic laws, as we discover in an hydraulic machine, or automaton, so admirably formed, as by the mere force of its construction to perform and continue the vital motions. ”

“ Objects of minor importance operate continually on our senses, but may escape the observation when preoccupied, particles of matter passing before our eyes induce us to close the palpebræ, yet the action is not always attended to. Also the common action of the heart and arteries are not the subjects of our consciousness; the stimulus of the contained blood continuing nearly the same, conveys no impression to the mind ”

“ We are informed that a fresh egg in consequence of being alive resists the cold, and is frozen with greater difficulty; but once frozen and thawed again it loses its living principle and power of resisting cold at once. It freezes now at the same temperature with other animal matter, shewing no longer any power of generating heat, or resisting cold. ”

“ If the egg does contain an independent principle of life why is not the chick evolved without the aid of other agents?
The last argument I shall notice on this fanciful hypothesis is not least in importance with the advocates for the independent principle but is one on which they place much reliance, viz., the contraction of muscles after removal from the body. ”

“ No person, at all conversant with the phenomena of the passions, will deny the connexion between the mind and vital functions. It will therefore be only necessary to observe in answer to the third proposition; that sensation is predicated on a comparison of the past, with the present state of impressions, and that all are relative to some change in the percipient organ; heat is only sensible, because it was preceded by a lower temperature. ”

“ When we compare the two conditions of life and death, and see that all the corporeal or material parts remain in the latter state, and know at the same time that in life there was some thing that produced the characteristick thereof, we may rationally conclude that the endowments of life was some very subtile or spiritous principle which resided in, and influenced those parts which remain even after it has vanished. ”

“ Portions of blood drawn from the veins of healthy persons were subjected to the influence of electricity, which were observed to separate sooner than other portions set by as standard marks, from which it was inferred that the stimulus must have acted on a principle of life, to increase its action. To this inference I shall only offer general objections. In the present state of our knowledge, we know that the blood though apparently homogeneous is resolvable by agents into several parts ”

“ From the most remote periods of antiquity, philosophers have not been inattentive to the peculiar differences that discriminate animate from inanimate matter, and under some modifications the distinction has been attributed to a principle called life, which not sufficiently understood in its nature, is only to be known by its phenomena, or symptoms. ”

“ Anatomical research has traced the ramification of the nerve through all the fibre entirely diffused even till lost in pulp, and no one I believe has reason to doubt the complete dependence of sensibility on the presence of the nerves, yet there is no instrument, however sharp, that can touch a single point in a muscle without producing a sensation more or less acute; which circumstance shews the entire distribution of the nerves. ”

“ Seeking for the medium through which this vital influence immediately operates, I am induced to turn to the brain as the point where all the powers of the animal appear more completely concentrated, and its continuations the (nervous elongations) as the active agents of life, existing more or less through the whole body. ”

“ That Fœtuses have in a few remarkable instances been ushered into a short lived existence without a brain, is advanced with some degree of elation by the supporters of the principle under consideration. Animals, from equally good authority, have been born without hearts: but will a few cases of lusus naturæ serve to disprove the importance of these organs to the animal economy? ”

“ In considering the condition of animals in their nascent state, we may readily understand, that their rudiments, composed of a pellucid congeries of parts, will freely transmit the light, and as there is no analysis of the ray, or proper reflection of it, it can make on the retina no impression, nor convey to the mind any perception of the existence of distinct parts. ”

“ For such reasons I would not consider any part of the living body independent of the common sensory, but I can suppose that the mind by disuse or disease may lose its power over some organs, as it sometimes does over even the voluntary muscles. ”

“ Life being rather the quality that distinguishes dead from living matter, and which may consist in an aptitude to action, and can remain for some time after its active effects cease to be obvious.
This aptitude will continue in some animals longer than others, probably owing to the peculiar manner in which they are influenced by stimuli; look at the large class of hybernating animals ”

“ In conclusion I will only observe, it is to the brain and its nervous system we should attribute the residence of vitality, which completely distributed and influenced by proper circumstances produce all the powers of the living system. ”

“ While other parts of the body, even bone, may be destroyed by pressure, the nerves resist its destructive influence, as is evinced in the ligature of the surgeon passed round them in awkward operation, for however tight it may be drawn ”

“ Satisfied that comparisons are always indelicate, and might in the present instance prove particularly offensive, I forbear to particularize advantages, but must, however, indulge in an expression of the gratification I feel in seeing the art of medicine once more assume to itself the form and character of a science ”

“ And therefore objects which are equable in their application, and continued for a length of time, affect us but slightly; are unattended to when present, and cannot be recalled when past, must consequently escape our consciousness. ”

“ And as we have not all the advantages attendant on the other physical sciences, having the operations of a living machine, if I may use the expression, to calculate, we must be content to move with a slower step. ”