페이지 이미지
PDF
ePub

are formed by two glands found in the eighth ring of the body (figs. 7 and 5 b); they present a most beautiful structure, being composed apparently of polygonal cells : in their interior are found little vermiform bodies which assist in the secretion of the fluid that forms the egg-capsules. The eggs are probably deposited by a spontaneous dehiscence or rupture of the body, there being no natural outlet. Fig. 9 represents a (probably) secretory organ met with in the ninth ring of the body. Its function is not known.

Whilst speaking of the circulatory system we should have mentioned that the general cavity of the body is filled with a fluid which surrounds all the internal organs. It contains numerous small granules of various sizes, very similar in appearance to those found in the quasi liver enveloping the intestine (fig. 15). This liquid is probably merely pure water which brings the needful oxygen to the capillaries of the Tubifex, and answers the purposes of respiration. Such an arrangement is met with in many annelides, and is known as the chylaqueous system.

Our little Tubifex not only presents us with a wide field for study and amusement in the investigation of its anatomy, but it actually forms the habitat of at least two very interesting forms of animal life. One of these is met with in the interior, the other attached to the exterior of the body. The animalcule which resides in the interior of the Tubifex is a species of Opalina; it is very minute, and is covered by spiral rows of cilia, giving it, when in motion, an extremly beautiful appearance. It is one of the lowest forms of animal life belonging to Ehrenberg's class Infusoria. The other parasite which we have met with in studying the Tubifex is the beautiful Vorticella. We have examined but few specimens without finding a cluster of these exquisite living forms attached to the head or tail of the worm. The Vorticella, like the Opalina, is very low in the scale of creation, but it is of an entirely different form : supported by contractile stems there are numerous cup or bellshaped bodies fringed round their margins with beautiful cilia.

Thus it will be seen that even in localities and substances which are repulsive to the ordinary mind, the inquiring student may find living forms of intricate structure performing complicated natural functions, and affording a habitat for still simpler but equally interesting forms of life. Even this imperfect and cursory review of the anatomy of the little Tubifex cannot fail to have afforded confirmation of the great truth, that all things are created in wisdom, and we may once more repeat that not only is it possible for the thoughtful man to read “sermons in stones," and find “books in running brooks,” but that even the muddy bed of a broad river yields its volumes for the edification of the inquiring mind.

[merged small][ocr errors]

Y anæsthetics are understood certain substances which D have the property of inducing a peculiar state of the nervous system called anæsthesia, and thereby rendering us insensible to pain. They rank among the most powerful, and, at the same time, most useful agents that man has hitherto obtained from the hidden treasures of nature. From the moment of his birth (and perhaps even some time before birth), man is liable to experience what is called pain. The human body is so organized that, in a state of perfect health, we feel nothing; and there are some persons, though few indeed, who pass through life almost without knowing what pain is, whilst others again are almost constantly in a state of suffering. When pain is felt in any part of the body, that part is not in its normal condition, it is no longer in the state of insensibility which characterizes perfect health.

But pain is not without its uses: it warns us from danger, and without its existence our own existence would infallibly cease. For instance, if no pain were felt when the hand or foot is placed in the fire, we should not be tempted to withdraw it unless we happened to see it consuming. Some time ago a labourer lost his leg by sleeping too near a lime-kiln; he felt nothing till he awoke, when it was too late. Likewise, if no pain were felt when boiling water, or some powerfully acrid substance, is poured down the throat, we should not be tempted to desist from introducing it into the body, and 40 our life would, sooner or later, be inevitably destroyed. In lower animals, where the organs of sensation cannot be detected 40 distinctly as in man, and in some where such organs seem indeed to be completely wanting, there is still an existing faculty equivalent to pain, and followed by similar effects : thus, if we touch the tentacles of a sea-anemone, in which organs we can find no nerve-fibres, the animal instantly withdraws them as if hurt, in the same manner as a dog would withdraw his leg if his foot were pricked with a pin. In the human body, we have three kinds of nerves : viz., the nerves of sensation, the nerves of motion, and the nerves of organic life, which govern the functions of digestion, respiration, secretion, &c. But these three kinds are so intimately connected in the animal economy that one of them may, in certain cases, react upon the others, so that all three are capable of giving rise to pain; the first directly, and the others indirectly, by acting through the first. But happily for us, the study of nature has placed in our possession several means of allaying pain; it has procured us a series of substances which act upon the nervous system so as to deprive it of its faculty of producing pain, sometimes partially, and sometimes most completely, without interfering in any great degree with the other functions of the body.

Some of these means of allaying pain consist in producing sleep, either perfect or partial. The physiology of sleep is little understood, and, indeed, next to life and death, sleep is perhaps the most inexplicable phenomenon inherent to our nature. At certain intervals, we feel an irresistible desire to repose, and sleep comes on gradually. Its influence is felt by certain portions of the nervous system; other portions never sleep. The nerves of organic life continue their functions during sleep, the heart beats, circulation goes on, respiration and digestion continue, but the nerves of motion and of sensation have momentarily lost their power; consciousness is gone, voluntary motion disappears, hunger and thirst are absent, and so likewise is pain. Such is complete or perfect sleep. But it happens sometimes that sleep is partial or imperfect, and then some curious phenomena are observed. Intelligence may be more or less active, and sensation may be possible to a greater or less degree, but never to so great an extent as in the waking state. Generally, in imperfect sleep, consciousness is only partial, volition incomplete, and sensation dull. This state of incomplete sleep gives rise to dreams and to somnambulism. The former are odd manifestations of the intelligence no longer completely conscious. The latter may be either natural or artificial (mesmerism).

In somnambulism the intelligence is more active than in an ordinary dream; the nervous system, only partially subdued by sleep, is capable of bringing into action the senses and motion, but the faculty of feeling pain is almost, if not entirely absent, and moreover the somnambulist has no consciousness of danger. Hence natural somnambulism, which varies in intensity from simple sleep-talking to the most remarkable physical and intellectual feats, is a dangerous condition, inasmuch as we are no longer able to take care of ourselves. However, somnambulists have frequently avoided dangers in the most astonishing manner.

Artificial somnambulism, or mesmerism, as it is sometimes termed, only differs from the latter in being produced by artificial means. In both cases, the nervous system is more or less subdued as in ordinary sleep; organic functions (respiration, digestion, &c.), continue, but sensation is incomplete or annulled, and the power of feeling pain often completely absent. The manifestations of the intelligence are similar to those in dreams. The somnambulist, whether his sleep be natural or artificially provoked, will generally answer questions that are addressed to him, and in artificial somnambulism, or mesmerism, the intelligence is frequently in an extraordinary state of activity. This activity is, however, never complete; consciousness is absent, and though memory is often remarkably precise, and certain other intellectual faculties acquire, for the time, an extraordinary development, it is absurd to imagine that somnambulists have the power of seeing into the future, &c., as many persons, unaccustomed to the study of physiology, have supposed.

Certain chemical substances have the peculiar property of acting upon the nerves and producing sleep, even when administered in very small doses. These substances act upon the nerves, as is proved by applying them directly upon a nerve, and induce a nervous state, in which no pain, however violent, can be experienced by the person submitted to their influence. They differ by this property from all other known substances. Some of these compounds are extracted from certain vegetables, others are produced artificially in the laboratory. Plants which contain these subtle and powerful agents have been marked by the human race for many centuries, but it was reserved for modern chemistry to extract the active principles themselves, in a pure state, and ascertain their composition and properties. Among these plants are the poppy, the mandrake, the hemp plant, &c.

The mandrake (Atropa mandragora) has been used for many centuries to allay pain. Eighteen hundred years ago, Dioscorides stated in his writings, that, in his time, it was given “to cause insensibility to pain in those who were about to undergo any cutting or cauterizing operations.” These persons, he tells us, “are thus thrown into a deep sleep, and do not perceive the pain.” The Greeks and Romans used the root of the plant steeped in wine. Pliny also mentions the use of the mandrake as possessing powerful narcotic properties, and as being used for injuries inflicted by serpents, as well as for surgical operations, in order to assure insensibility to pain. Apuleius has also spoken of it in a similar mannor.

Atropa mandragorl, like the Atropu boulonna (deadly nightshade), and other plants of the genus Atropa, belongs to the family of Solanee, which contains also the tobacco plant

VOL. 11. ---SO. V.

(Nicotiana), the potato (Solanum), and several other important vegetables. It owes its pain-allaying properties to a principle called Atropine, a crystalline alkaloid, first discovered in Atropa belladonna. Though seldom or ever used at present, the root of the mandrake was frequently employed, with opium and other narcotic drugs, in ages gone by. Theodoric, a pupil of Hugo, who lived in Italy during the latter half of the thirteenth century, gives us, in his work on surgery, the following curious recipe, which shows that he was perfectly aware that surgical operations could be performed without causing any pain to the patient, by employing certain drugs. His indication runs as follows:-" The making of a flavour for performing surgical operations, according to Dominus Hugo : -Take of opium, of juice of unripe mulberry, of hyoscyamus, of the juice of the hemlock [Õicuta), of the juice of the leaves of unripe hemlock, of the juice of the wood-ivy, of the juice of the forest mulberry, of the seeds of the lettuce, of the seeds of the dock that hath a large apple [Datura], each an ounce; mix all these in a large brazen vessel, and then place in it a new sponge ; let the whole boil as long as the sun lasts in dog-days, until the sponge consumes it all. As oft as it is required place this sponge in hot water for an hour, and let it be applied to the nostrils of him who is to be operated upon, until he has fallen asleep, when the operation may be performed.”

Here we have opium, the narcotic juice of Papaver somniferum, Hyoscyamus niger, Cicuta virosa, and Datura stramonium, together with the less active lettuce, some of the most powerful narcotic vegetables known to us at the present day.

In 1579, Bulleyn, an English writer,, described a means of putting patients to sleep, in order to practise the operation of lithotomy. He employed the mandrake. And in 1608, Baptista Porta, in his work on “Natural Magic,” gives various receipts for medicines producing insensibility to pain. Among them is one for a “sleeping apple” (Pomum somniferum), composed of mandrake, opium, &c., the flavour of which is prescribed to be inhaled by the nose. In the same work it is stated, that certain soporific plants will yield a “quintessence" which will overwhelm one with profound sleep. This is not surprising, when we know that the Magisterium opi, an extract of poppy or sort of impure morphia, figured in the Pharmacopeia as early as the seventeenth century.

Of late years, the mandrake has almost completely given way to the deadly nightshade (Atropa belladonna), a plant which is well known to have greater power in annulling sensibility than any plant now in use, unless it be the aconite (Aconitum napellis).

« 이전계속 »