Acaventy of Medicine, Corontn. 1499 Presented by \ Gc, Pete = sired BIOPLASM: A CONTRIBUTION TO THE PHYSIOLOGY OF LIFE. Digitized by the Internet Archive in 2008 with funding from Microsoft Corporation http://www.archive.org/details/bioplasmintroducOObealuoft ™'\ BIOPLASM: INTRODUCTION TO THE STUDY OF PHYSIOLOGY & MEDICINE. BY 7 ae J b uth ob TT LIONEL 8 “BEAM M. Bs, F RS Fellow of the Royal oe ge 0 i Phe ns, Physician to King’s Colleg Hospital, and Pro, r Pc rth lien Anatomy in King’s Tr eallege, London. WITH NUMEROUS ILLUSTRATIONS. LONDON: J. & A. CHURCHILL, PHILADELPHIA : LINDSAY & BLAKISTON. 1872. [All rights reserved.] LONDON: HARRISON AND SONS, PRINTERS IN ORDINARY TU HER MAJESTY, ST. MARTIN'S LANE. PRE EAC Ky Ix this little book an attempt has been made to determine and explain the nature of some of the most important changes which are characteristic of and peculiar* to living beings. Technical terms have been as far.as possible avoided. Many of the matters I have thought it desirable to: €onsider are, however, complicated and intricate, indeed of a character not generally discussed in text books, and I fear that, in some instances, I have failed to render what I have tried to convey as clear and as intelligible as I desired. Most of the imferences I have drawn concerning very difficult questions rest upon actual facts of minute research, but I have ventured to speculate upon seme matters which are at present beyond the sphere of observation. The reader will probably admit that the first part of his task is not a difficult one, but as he progresses I fear he will find the book becomes more difficult to read. In the last four lectures some rather abstruse points in physiology have been brought under the student’s notice, but the facts upon which the con- clusions so far deduced have been based are recorded and explained. vi PREFACE. Some of the investigations have been published in detail in memoirs that will be found in the Phil. Trans. of the Royal Society, the Trans. of the Microscopical Society, and elsewhere. The very last observations upon which I have been engaged have been included in Lecture XII, and four of the drawings in Plates XV, XVI, XIX and XX have been prepared to illustrate them. How far the experiment of introducing the results of recent investigations into a little text book has been successful I must leave others to judge. Myaim in this and other works has been not only to teach facts, but to encourage students to educate themselves for original enquiry in order that they may add new facts to those already known, and thus advance the department of natural knowledge they have selected for their life’s work. 61, GROSVENOR STREET, September, 1872. CONTENTS. INTRODUCTION. Uninterrupted progress of Physiology ee Importance of good specimens : Magnifying powers employed Living and non-living . Changes occurring during life Of the Matter of Living Beings. Living particles oe we Of obtaining living particles from air Two kinds of matter in a living particle Two kinds of living particles . ae An elementary part First stage of being of every living thing Form, SPenenire, colour, mechanism Conversion of the non-living into the living Living matter or bioplasm Protoplasm .. sf E He ee Death of bioplasm .. Sea eae Products of the death of bioplasm be Bioplasm haying died cannot live again A crystal may be re-cr ystallised A magnet may be re-magnetised A dead thing cannot be re-vitalised. . Of Bioplasm. Different kinds of bioplasm .. 3¢ Origin of bioplasm The changes ef bioplasm and its conversion into tissue Different tissues in the body . Young growing tissues contain much water All organs come from bioplasm PAGE Onwwnr OM ONNIADHD Nee Pp Vill CONTENTS. PAGE Bioplasm in health and disease, and at all ae ar fee ls) Of difference in structure .. oe l6 Variation in structure not due only to varying conditions 18 Examples of Bioplasm in Tissue. A young leaf and its bioplasm 30 ae ee ee) Cartilage and its bioplasm -. a Bk ae “ee Epithelium and its bioplasm. . ye sta fs Bee e740) Mucus and its bioplasm. ° .. ee x of ee Origin and Nutrition of Bioplasm. Movements of bioplasm - ie oe ac a0. a Origin of new centres. . ce xe ve 57 eo ek Nutrition of bioplasm . sca aes How pabulum may be br ought near to the bioplasm gan He: Organs for introducing food. . 36 oe Ae an wee Distribution of nourishment. . ore 56 a 35) The heart a¢ .. 24 Rapid growth of bioplasm i in the adult and in old a age .. 20 Rapid growth of bioplasm in disease oe re oe 2a Pus corpuscles . we 59 Be ee Lc «. 26 Of the Egg and of Development. The ovum oregg a a ye as ot ae Of development as dc oe = os eo Interstitial channels . . as rr Be oe 23 OU Vessels. . : = =A am aE re a Strictures and organs . oe 5c ae ae Sees! Alimentary canal |. wi es Say uct! Glands for producing solvent fluids a Se -. 32 The blood 36 4 fe 3 oe cop, fei Bioplasm of the blood . 40 ae 42 5% ne MO Red blood corpuscles. . ; ic oat Liver for making bile and altering the blood he .. 384 Lungs for respiration. . oe are = x0 Beebe 313, The kidneys for secreting .. Re ve ae 2 BO Cutaneous glands... AG 43 “LO - Organs inactive during embry vyonic life oe =e ae ROS Temporary organs .. 36 36 ac be 7.) ets The skeleton .. se re = ae 30 ob. P36 Nervous tissues Ae ic 7 5c sta eae The muscular tissue .. < ie ys me eros The skin bis th a2 ae a; to cele fre om 1860 to 1865 Ac ZS, Distribution of nerves ate iia prenet aaeeele on the frog Ao AS Distribution of nerve fibres to the muscles of the hyla or green-tree frog 5 258 Distribution of nerves to the ames of erhienintee 258 Distribution of nerves to the muscles of the maggot 259 Nerves to the muscles of the leech .. 5 260 Of the nerve tufts, nerve eminences, and Nervenhiigel seen in connexion with certain muscular nerves 261 Nerve tufts are not terminal organs but networks. . 267 Distribution of nerve fibres to the elementary miseulae fibres 268 Nerve tufts exceptional , oe oe 5 .. 268 Of the so-called “ nerve tufts” in the breast muscle of the frog 269 Arrangement of nerve fibres in other forms of striped : muscle, as the branching fibres of the tongue, muscu- lar nbres of the heart and lymphatic heart of the frog wa 200 Of the finest nerve Heese Rinch eleeace the “suede 273 Diameter of the finest nerve fibres of muscle . 274 Reply to adverse criticism ©. . 275 The Blood-vessels and their Action. Circulation of the blood in the vessels 280 Importance of a knowledge of structure of the aise 283 Views regarding the structure of the capillaries .. «. 283 Protoplasm walls of the capillaries .. 56 5€ 284. Bioplasts or nuclei of the capillaries 287 Of the action of the tissue of capillary vessels duri ing life 288 Of the action of the poe of the ecsemanes during I life 289 Of the arteries... os i 291 Of the veins .. a ate oe 292 Examination of Ser erias ais veins .. 296 Of the action of the segue muscular fibre eels 299 XV1 CONTENTS. Arrangement of the Nerves distributed to Vessels. PAGE Distribution of nerves to the arteries of the frog .. .. 3800 Distribution of nerves to the arteries of mammalia Ae EY & Distribution of nerves to veins ae = 4h >» 805 Of the nerves distributed to capillaries .. .. 306 Arrangement of nerve fibres distributed to capillaries .. 308 Central origin and peripheral connections of nerve fibres distributed to capillaries ; 309 Recent observations on the distribution of nerves to the capillari ies of the bat’s wing .. 313 The action of the nerves distributed to the capillary vessels... : 320 Are the nerve fibres of the capillaries sensitive # Pear .. 320 Are they motor? 2 sie +o eud Are they nutritive or secretory in their action? -. .. 322 What is their office? .. : 3k .. 323 They may be concerned in general sensation o .. 323 Their connection with ganglia a2 5 $5 .. B24 Physiological experiments .. 325 Of the self-acting mechanism by which the supply of blood to tissues is “regulated 5 : .. 327 Influence of the ves 331 Action of the nerve fibres of the capillary vessels i in | inflam- mation .. 3382 Alteration of the nerve fibres and ‘capillaries in 1 chronic disease .. es Su ‘ie ae Be «2 Oo AN INTRODUCTION TO PHYSIOLOGY AND MEDICINE. BEOPEAS M. LECTURE I. Introductory—Of very Minute Living Particles—The First Stage of Being of every Living Thing—Form, Structure, Colour, Mechanism—Formation of the living from the Non-living—Of Living, Forming, Growing Matter, or Bioplasm—Protoplasm— Death of Bioplasm—The Crystal, the Magnet, and the LInving Thing—Difierent kinds of Bioplasm—Origin of Bioplasm—Changes in Bioplasm, and of its Con- version into Tissue—Tissues at all Ages, in health and im disease, contain Bioplasm—Difference in structure not due merely to variation of condition. 1. Uninterrupted progress of Physiolegy. — No branch of natural knowledge exhibits such wonderful and uninterrupted progress as physiology. Not only is the superstructure being constantly added to and altered at the same time, but the very foundations are for ever being extended, improved, and renovated. No wonder, then, that, in our anxiety to add to exist- ing knowledge, we sometimes misjudge facts and misinterpret phenomena. No wonder that observa- tions regarded as very accurate at the time they were made, afterwards prove to have been erroneous, or that B 2 IMPORTANCE OF GOOD SPECIMENS. the conclusions of one observer should be strangely at variance with those of another. Like the living things of which it treats, physiology is incessantly changing, and the true physiologist endeavours not only to add to existing knowledge, but so to add that further changes, which he knows are inevitable, may be made with the least possible derangement. In progressing, he desires to provide for further, and he hopes unceasing, progress. 2. Importance of good specimens.—F ew things are more difficult than to observe and interpret correctly the mere structure of the tissues of man and animals. It is, therefore, all-important to obtain specimens which shall demonstrate clearly any new facts we think we have proved. Every effort has been made to illustrate by specimens the views J shall advance in these lectures; but the difficulties in the way of obtaining and preserving good preparations, which positively demonstrate at one view the facts upon which conclusions concerning structure and growth have been based, are so great that I scarcely think my efforts can be attended with complete success. 3. Magnifying powers employed.—The specimens which I shall have to describe have all been prepared upon the same definite plan, and have been preserved in the same medium.. They have been examined under objectives magnifying from 50 to nearly 5,000 diame- ters.* In order that some idea may be formed of the degree of amplification of the one-fiftieth object-glass made for me by Messrs. Powell and Lealand in 1864, I may be permitted to mention that if it were possible to see a hair in its entire width under this power it would appear to be nearly one foot in diameter, and an object an inch in height would be made to appear as if it was 250 feet high. 4, Living and non-living.—I shall have to direct * Proceedings of the Royal Society, January 19, 1865. “ How to work with the Microscope,” 4th edition, p. 286. o CHANGES OCCURRING DURING LIFE. oO attention to some facts which have led me to conclude that certain phenomena manifested by part of the material substance of which all living things are composed, are peculiar to the living world ; that be- tween the living state of matter and its non-living state there is an absolute and irreconcilable difference ; that, so far from our being able to demonstrate that the non-living passes by gradations into, or gradually assumes the state or condition of, the living, the tran- sition is sudden and abrupt; and that matter already in the living state may pass into the non-living con- dition in the same sudden and complete manner ; that, while in all living things chemical and physical actions occur, there are other actions, as essential as they are peculiar to life, which, so far from being of this nature, are opposed to, and are capable of overcoming, phy- sical and chemical attractions. And I think the evidence which I shall adduce will prove conclusively that the non-living matter is the seat of the physical and chemical phenomena occurring in living beings, but that the vital actions occur in the living matter only. Moreover, we shall see that this living matter, which exists in every living thing in nature, can be easily distinguished from all matter in the non-living state. 5. Changes occurring during life—I shall not con- fine myself tc the demonstration of the structure of tis- sues which have been removed from the dead body, but shall endeavour to describe what probably takes place during life while these tissues are being developed, are growing, and are acting each in its own peculiar way. And if I fail in my attempt to give, as it were, an account of the life-history of a tissue, I trust I shall at least be able to assign a more definite meaning to the words “life,” “living,” “vital,” &c., than has been done hitherto. It would be presumptuous in me to hope to place on a more sure foundation the science of the living, but I shall do my utmost to B 2 4. LIVING PARTICLES. rescue physiology, for a time at least, from being con- sidered a mere subsection of physics. : G. Living particles.—It is difficult for the mind to realise the wonderful minuteness, the extraordinary number, and the almost universal distribution of par- ticles of living matter. Not only are they found in and upon the earth and water, but the air teems with them, and is, as is well known, the medium by which some particles of comparatively large size and even of complex organisation are carried from the place of their formation to the seat of their development and growth. But of microscopic germs the air contains vast quantities differing entirely in their nature, their 'mode of crigin, and in the results of their develop- ment. Living particles giving rise to various forms of microscopic fungi are wafted by currents of air into situations favourable for their development, and may become the active agents in every kind of fer- mentation and putrefaction, as has been proved by Pasteur. In the same way there is reason to think particles of living matter capable of giving rise to the most serious and fatal diseases of which man is the subject are carried to an organism which is in a state favourable for their reception and germination. No doubt millions of such liying particles perish for every one that germinates. Some are much more easily destroyed than others. Certain kinds retain their vitality for a comparatively long time in a moist warm ‘atmosphere, and it is not improbable that they may even grow and multiply, and perhaps produce particles differing from them in properties or powers. Some of these particles possess inherent motion, and it is probable that they climb, as it were, through still and moist air, just as amcebee and certain other living par- ticles are capable of climbing in any direction through water which is in a state of perfect rest. Minute par- ticles possessing these inherent powers of active move- ment can insinuate themselves into the slight chinks OF OBTAINING LIVING PARTICLES FROM AIR. 5 in fully formed tissues in every part of the body, and may easily make their way along the crevices between protective epithelial cells into the tissues beneath, and then through the thin walls of the smallest vessels into the blood. 5. Of obtaining living particles from air.— Very minute living particles may be obtained from the air in many ways. Perhaps the simplest process is to allow the vapour of the atmosphere to condense on the sides of a perfectly clean glass vessel filled with ice. The drops of water as they trickle down the sides are to be received into a conical glass, and any living particles entangled in the fluid can be detected upon microscopical examination with a sufficiently high power. In many instances two kinds of particles will be found—one soft, exhibiting moverents in the fluid in which it is suspended; the other spherical or oval in form, comparatively firm, and possessing con- siderable resisting power. The first are often ex- tremely minute, and so very transparent that they can only be distinguished from the medium in which they are suspended by very high magnifying powers, used with the greatest care and under the most favourable circuiestances. 8. Two kinds of matter in a living particle.—F ur- ther examination enables us to demonstrate that the particles last spoken of are composed of matter in two different states: 1, a firm envelope closed at all points; and 2, a little delicate transparent matter within this, and resembling the material of which the first kind of particles seems to be entirely composed. I shall presently endeavour to show that these cap- suled particles of living matter were not always so inclosed, and that the capsule was, in fact, formed in consequence of changes taking place upon the surface of a particle of living matter like the particles first referred to. 9. Two kinds of living particles.—Living things 6 AN ELEMENTARY PART. in water, and living things on or in the ground, may in like manner be divided into (1) those which con- sist of living matter capable of moving in every direc- tion, of dividing and subdividing, and invested only with a very thin layer of fluid or semifluid matter, and (2) those which are covered with a layer of a more or less resisting material, which interferes with or entirely prevents such movements of the living matter as have been referred to above. 10. An elementary part.—So also the elementary parts of which all the tissues and organs of man and all the higher animals are composed are found to con- sist of these two classes of particles—the first exhibit- ing the general characters already described, the last manifesting a great variety of form, structure, and properties, according to the arrangement, character, and composition of the external or enveloping matter. The great difference between particles of apparently naked matter and particles enclosed in a thick en- velope or capsule is but a difference of degree. The first, or apparently naked particles, are perhaps in- vested with so very thin a layer of soft and perhaps fluid formed substance that it follows the movements of the living matter, and is almost invisible; while in the last this formed matter has increased im thick- ness, and has undergone condensation, so as to inter- fere with the free motion of the living matter within, or, at most, to permit it only to move round and round within its prison wall. Our investigation is therefore narrowed to the study of the changes taking place in the transparent living matter itself, and the production of the material upon its surface. il. First stage of being of every living thing.— Even man and the higher animals, as well as every other living thing, begins its life as a minute spherical particle, hardly to be distinguished from those minute particles of simple living matter suspended in the air (§ 6). The particle consists of colourless trans- FORM, STRUCTURE, COLOUR, MECHANISM. 7 parent semi-fluid matter capable of moving in every part and in all directions. Man and animals, plants, fungi, monads, thus exhibit the same appearances, and the matter of which they consist exhibits similar characters. Each primitive particle was derived from matter like it which existed before it. It was simply detached from a parent mass. 12. Form, structure, colour, mechanism.—TI hope to convince you that all form, colour, structure, me- chanism, observed at a later period in the life-history of living things, result from changes in this primary structureless, colourless material. This primary matter of living beings which looks like mere jelly or a little clear gum or syrup, exhibits actions and un- dergoes changes unlike those occurring in every other kind of matter known to us. Although we can make many different substances exhibiting very remarkable properties, and machines capable of doing many kinds of work, and constructing wonderful things; no one has ever been able to obtain any chemical compound having the properties of this living speck, or any mechanism which acts as this wonderful transparent matter acts. The colourless, structureless matter, characteristic of and peculiar to all life on the earth, and in air and in water, is capable of moving in every part and in every direction. The movements are not such as are produced by vibrations communicated to the fluid or semi-fluid substance from matter in vibra- tion in its neighbourhood, but the impulse proceeds from within the matter itself. The cause of the move- _ ment has not been ascertained. The facts will be more particularly described in Lecture IV. 13. Conversion of the non-living into the living.— Every kind of transparent colourless living matter takes up lifeless material which it changes. Certain elements of this are assimilated and converted into matter like that of which the living matter consists. After a time the matter which has become living under- 8 LIVING MATTER OR BIOPLASM. goes further change. It, or part of it, ceases to mani- fest its remarkable properties, and becomes resolved again into non-living substances, which are sometimes gaseous, sometimes fluid, sometimes solid. And very often the same living matter is resolved into sub- stances in these three physical states. The solid matter that is formed may exhibit structure, or it may be structureless. It may be passive, or it may possess very active non-vital properties, as will be particu- larly discussed further on. 14. Living matter, or Bioplasm.—This wonderful matter to which I shall have frequently to refer in every part of this volume, moves and grows. Every- thing else in nature may be moved and caused to increase by aggregation—by particles being added to those already collected; but this alone of all matter in the world moves towards lifeless matter, incor- porates it with itself, and communicates to it in some way we do not in the least understand, its own tran- scendantly wonderful properties. The matter in ques- tion is living matter. This matter, then, which is found in all living things, and in these only, is peculiar, and is to be distinguished from matter in every other state, be it gaseous, fluid, solid, crystalline, or colloid, structureless or having structure. This is the matter which lives. It may be correctly called living or forming matter, for by its agency every kind of living thing is made, and without it, as far as is known, no living thing ever has been made, or can be made at this time, or ever will be made. As the germ of every living thing consists of matter having the wonderful properties already mentioned, I have called it germinal matter ; but the most convenient and least objectionable name for it is living plasma or bioplasm (8.0 life, 7haoua plasm, that which is capable of being fashioned). Bioplasm is found in every tissue in every part of the living body as long as life lasts. 15. Protoplasm.—The matter which I have termed DEATH OF BIOPLASM. 9 forming, living or germinal matter, to which I have more recently given the name Dioplasm, has been lately spoken of by others as protoplasm. And it has been hinted, though not definitely stated in print, that in my memoirs | had simply altered the name of matter which had been previously described by others. But such is not the fact as the most influential of my opponents well know. The word protoplasm would have been used by me had the term been restricted to the matter of the tissues, which I termed living or erminal matter, and which I showed, in my lectures at the College of Physicians in 1861, underwent con- version into formed matters, and was concerned in forming all tissue. But under the term protoplasm has been included, the contractile tissue of muscle, the axis cylinder of the nerve fibres, processes of nerve cells, and many other textures which un- doubtedly consist of formed material, and are entirely destitute of the properties which invariably belong to my “germinal matter,” or bioplasm.* Moreover, the nucleus and nucleolus were by many writers considered to be distinct from the protoplasm. On the other hand I showed that the nucleus and nucleolus were living. My bioplasm, germinal, or living matter therefore includes both nucleus and nucleolus as well as some forms of the protoplasmic matter of authors. Moreover, my paper on germinal matter had been written before the subject had been at all discussed, either on the continent or in this country, from the point of view I had taken up. Max. Schultze, who wrote after me, concerning the nature of the cell-wall, remarked that this structure had for me “only an historical interest,’’ and objected to my conclusions. 16. Death of Bioplasm.—All bioplasm must die. * But Prof. Huxley has given a yet wider signification to the word protoplasm, and makes it stand for almost anything organic. His new “ protoplasm” may be dead or living, may exhibit struc- ture or be perfectly structureless ; nay, it may be even boiled or 10 DEATH OF BIOPLASM. By its death marvellous things are produced, and wonderful acts are performed. Every form in nature—leaves, flowers, trees, shells; every tissue— hair, skin, bone, nerve, muscle—results from the death of bioplasm. Every action in every animal from the first instant of its existence to the last, marks the death of bioplasm, and is a consequence of it. Every work performed by man, every thought expressed by him is a consequence of bioplasm passing from the state of life,—ceasing in fact to be bioplasm, and becoming non-living matter with totally different properties. To produce these results the death of the bioplasm must occur in a particular way, under par- ticular circumstances, or conditions. These are often very complex, and as yet very imperfectly under- stood; but it will be my business, to endeavour to elnteidiaipe them, as far as [ am able, in this volume. 1%. Products of the death of Bioplasm.—W hen the life of a mass of bioplasm of any kind is suddenly cut short, lifeless substances having very similar roasted without ceasing to be protoplasm! The protoplasm of Huxley includes both my bioplasm and formed material, and although these things are to be distinguished from one another by so many essential characteristics, Mr. Huxley contimues to affirm that both are protoplasm, though he is obliged to admit that one is “ modified” protoplasm. More than twenty years ago, Huxley added to the confusion at that time existing on the cell theory, by affirming that the endoplast (my germinal matter) was unimportant, and but an accidental modification of the nucleus, which was sometimes altogether absent. He wrongly attributed formative properties to the formed lifeless periplastic substance, which is perfectly passive. But his new “ proto- plasm” is a compound to which it would be difficult to find any- thing analogous even in the annals of conjectural science. In . that. substance he has re-united the very matters he had before “ differentiated,’ and has given rise to a further confusion of ideas by calling such things as white of egg protoplasm. Until, therefore, the term ‘“ protoplasm” is by common consent restricted to matter while it is living and growing, I must employ for the latter some other word which more accurately defines it, and “bioplasm” seems upon the whole the most convenient, as well as the shortest word that can be selected. BIOPLASM HAVING DIED CANNOT LIVE AGAIN. 11 properties result. These substances belong to four different classes of bodies. One separates spon- taneously soon after death. Another is a transparent fluid, which ‘is coagulated by heat and nitric acid. The third consists of fatty matter; and, the fourth, comprises certain saline substances. When a mass of bioplasm dies it is in fact resolved into—1, fibrin ; 2, albumen; 8, fatty matter; and 4, salts. These things do not exist in the matter when it is bioplasm, but as the latter dies it splits up into these four classes of compounds. 18. Bioplasm having died cannot live again.— Once dead, bioplasm ceases to be bioplasm, and is resolved into other things; but these things that are formed cannot be put together again to reform the bioplasm. They may be taken up by new bioplasm, and so converted into living matter; but the bioplasm that existed once can never exist again. All bio- plasm must die, but re-living is, as far as we know, impossible, and scientifically is inconceivable. 19. A crystal may be re-crystallisea.—A_ crystal may be dissolved in water and new crystals formed, but a particle of bioplasm can no more be dissolved and reformed than a man can be dissolved and re-erystal- lised. The difference between living matter and life- less matter—between bioplasm and thé things which result from its death, is absolute. The change from one state to another is sudden and complete. 20. A magnet may be re-magnetized.—The steel of which a magnet is composed can undoubtedly be unmagnetized and re-magnetized as often as we will; but the analogy which Prof. Owen has sought to establish between the magnetized steel, and the living organism is surely most fanciful. What two things are more unlike than a piece of steel and a dead organism, and what phenomena that we know of have less in common than magnetic phenomena and vital phenomena ? eins) 1 A DEAD THING CANNOT BE RE-VITALIZED. 21. A dead thing cannot be re-vitalized.—Prof. Owen has remarked that “there are organisms (Vibrio, Rotifer, Macrobiotus, &c.), which we can de- vitalize and revitalize, devive, and revive many times!” But, the Professor in this sentence uses two words having different significations, as if they had the same meaning. To revive and revitalize are two very different things. That which is not dead may be revived, but a thing that is dead cannot be revitalized. The animaleule that can be revived has never been dead. The half-drowned man who revives has never died. The difference between the living state and the dead state is absolute, not relative. The matter from which life has once departed cannot be made to live again. 22. Different kinds of Bioplasm.—Since all bio- plasm possesses certain common characters, and the bioplasm of one plant or animal produces formed matter of a very different kind from that resulting from: another portion of bioplasm, we must admit that in nature there are different kinds of bioplasm indistinguishable by physics and chemistry, but en- dowed with different powers, flourishing under differ- ent circumstances, consuming different kinds of pabulum, growing at a different rate and under very different conditions as regards temperature, moisture, light, and atmosphere, possessing different degrees of resisting power, and dying under very different cir- cumstances, having varying powers of resisting alterations in external conditions. 23. Origin of Bioplasm.—Concerning the origin of bioplasm, we have no knowledge or experience. Lucretius fancied that atoms came together under certain circumstances, and that thus living things or their seeds were produced. Some of the most ad- vanced minds of the present day entertain a somewhat similar opinion. But both ancients and moderns base their doctrine on conjectures and their own peculiar CHANGES OF BIOPLASM INTO TISSUE. 13 interpretation of facts. When these fail, they resort to dogma. The idea of spontaneous generation is being continually revived. New facts are advanced in its favour, but examination proves that the supposed new facts are not facts at all. Whether one primi- tive mass of bioplasm was caused to be, in the first creation, or five, or fifty, or whether thousands or mil- lions rushed simultaneously or successively into being, is open to discussion, but the arguments in favour of the view that a minute mass of structureless bioplasm was the first form of living thing, are so overwhelm- ing that they must carry conviction. The formation of tissues, organs, limbs, must have been a subsequent and very gradual operation, proceeding slowly by gradational changes according to certain laws. All evidence teaches us that from the first beginning of life, bioplasm has proceeded from bioplasm, and the formation of bioplasm direct from non-living matter is impossible even in thought, except to one who sets absolutely at nought the facts of physics and chemistry, and is perfectly blind as regards the ordinary phe- nomena of the living world continually succeeding one another before his eyes. 24. The changes of bioplasm and its conversion into tissue——A mass of bioplasm exposed to certain special conditions which differ as regards heat, mois- ture, pabulum, and which vary with every kind of bioplasm, grows, divides, and subdivides into multi- tudes of masses. Each of these grows and sub- divides in the same manner until vast numbers result. By these apparently similar masses of bio- plasm, different tissues, organs, and members are formed. Some give rise to tubes which carry the nutrient fluid to all parts of the body. Some are concerned in taking oxygen from the atmosphere and giving up carbonic acid to it. Others separate materials resulting from decay, and convert these into substances which can be easily removed altogether 14 DIFFERENT TISSUES IN THE BODY. from the body. Other collections of bioplasm give rise to bone, to nerve, to muscle, and other tissues, while from others, organs so delicate as the eye and the ear proceed by gradual process of development, and convince us of the marvellous and inexplicable powers possessed by the formless bioplasm by whieh alone any of them could be formed. At length all the complex and elaborate forms of apparatus which make up the body of a living creature result. These excite our wonder the more thoroughly we study them, whether in what we call the lower or the higher creatures. These organs and structures per- form their appointed work for the appointed time, decay, and are resolved into formless ‘matters of interest to the chemist as well as to the anatomist and physiologist. 25. Different tissues in the body.—The body of a living animal is composed of many different tissues performing very diiferent acts, and designed from the first to fulfil different purposes as proved by the fact that each working tissue has to pass through several stages of formation, during none of which does it work or serve any useful purpose. But these stages of inaction were necessary for its construction ; and the ultimate form it was to take, and the duty it was to discharge, must have been determined from the first, when it was without form, and when no one could have premised either the form it was to assume, the work it was to do, or say why it existed at all. Bone and flesh or muscle, and cartilage or gristle, cuticle, nail, and hair, nerve, fibrous tissue, are ex- amples of different tissues. The tissues of the body change with age. The muscles of a young man are, weight for weight, more powerful than those of an old person ora young child. The tissues vary under dif- ferent conditions. In health the same muscles and nerves will do far more work without fatigue than they YOUNG GROWING TISSUES CONTAIN MUCH WATER. 15 can perform at all when the person is out of health. The tissues of the aged are dryer than those of the adult, and the tissues of the infant are very soft and succulent. The tissues lose water and become firmer, tougher, and some of them more brittle as age advances, and the rate of nutrition and growth are modified accordingly 26. Youngs srowins tissues contain much water.— The succulent tissues of the young grow fast, but the dry textures of the aged shrink and waste instead of growing. The rate at which a tissue grows varies greatly at the different periods of life. All the different tissues are formed at a very early period of lfe—long before birth, at which time all the tissues exist though in a very soft and succulent state, and are easily injured, owing to their delicacy and want of firmness. This difference in the rate of growth at different ages is due entirely to the more ready access of pabulum at the early stage, as will be more fully explained in another lecture. 24. All organs come from bioplasm.— All the dis- similar tissues of a man are represented by the soft transparent bioplasm which is of the same consistence throughout and possesses the same character in every part. At the first the quantity of this bioplasm is so very small that it can only be seen through a micro- scope. It looks perfectly clear, and there is no indi- cation of structure in any part. Yet the skin and bones and muscles and all the other organs ulti- mately come from it. It takes up food and increases. Gradually certain portions begin to form one tissue, and other portions another, and so on, until indica- tions of all the different textures are to he made out, but bemg so soft and delicate their examination re- quires the greatest care. 28. Bioplasm in health and disease and at all ages. —The bioplasm in all living things undergoes change. The lifeless food we take becomes converted into bio- 16 OF DIFFERENCE IN STRUCTURE, plasm, and then this latter is changed into the lifeless nutrient materials which are taken up by the several forms of bioplasm which are concerned in the forma- tion of the tissues. But bioplasm exists at all ages. It is to be detected in every tissue, be it healthy or diseased; simple or complex. Without it the tissue could not grow, and could not be repaired if it was injured. Without this it could not be said to live. In fact, the tissue that is formed is not living. The bio- plasm only is alive, and the proportion of bioplasm decreases as the tissue grows old. At first the little speck of matter out of which the man or animal or plant is: to be formed consists entirely of bioplasm, then soft temporary tissue appears, but the propor- tion of bioplasm to tissue remains very considerable for some time. Gradually, however, the tissue in- creases, and the proportion of living matter decreases, at last becoming so small that in many textures it does not amount to the ;3,th part of the whole. In many cases this small particle of living matter dies, and then the tissue is incapable of further change. It is all dead. If injured it cannot be repaired. It is no longer nourished. It no longer performs its function. It may yetremain connected with the living body, but itis as dead as the lifeless dried up leaf that still clings to the living stem, though every vital connection has long since been severed. 29. Of difference in structure.—On taking a gene- ral survey of living things, the untrained student is impressed by the very wide and apparently irrecon- cilable differences in appearance aud general charac- ters exhibited by the multitudes of living forms familiar tohim. A star-fish and an ox, a butterfly and a fish, an oak and a medusa, seem to differ from one another at least in as great a degree as any one of them dif- fers from a stone, from water, or from air. But, on the other hand, after careful and prolonged study, the student becomes so familiar with the many points OF DIFFERENCE IN STRUCTURE. 17 in which these things resemble one another that soon it becomes difficult for him to believe that, different as all are from stones and inanimate objects of every kind, they are not very closely related to one another ; and belief in this view may be strengthened by de- tailed research with the aid of very refined methods of investigation. The student will undoubtedly discover certain essential points in which all agree, and although the living things referred to differ from one another so enormously in dimensions, he soon finds out that the elementary parts of which the textures of all are composed differ comparatively slightly from one another even in size, while in general structure and appearance they are really much alike. Nor is any great difference in chemical composition to be demonstrated by chemical analysis. Moreover it can be shown that certain phenomena connected with the increase of tissues are common to them all, and when each is examined at a very early period of its forma- tion, the resemblance between many dissimilar tissues is found to be so close that it might be inferred that all were identical at first, and that the ultimate divergence was due rather to the different circumstances under which each was evolved from the homogeneous than to any inherent peculiarities, properties, or powers of the bioplasm that evolved them. There-is, indeed, a period in the development of every tissue and every living thing known to us when there are actually no structural peculiarities whatever—when the whole or- ganism consists of transparent, structureless, semi- fluid living bioplasm—when it would not be possible to distinguish the growing moving matter which was to evolve the oak from that which was the germ of a vertebrate animal. Nor can any difference be dis- cerned between the bioplasm matter of the lowest, simplest, epithelial scale of man’s organism and that from which the nerve-cells of his brain are to be evolved. Neither by studying bioplasm under the Me c 18 VARYING STRUCTURES. microscope nor by any kind of physical or chemical investigation known, can we form any notion of the nature of the substance which is to be formed by the bioplasm, or what will be the ordinary results of its living. 20. Variation in structure not due only to varying conditions.—And yet it would be childish trifling and mere playing with the facts of nature to assert, as some have done, that the character of the material produced and the properties not only of the tissue but of the bioplasm that produced it, depend in all cases upon the conditions under which life is carried on, merely because it has been found that alteration in the conditions under which life is carried on in some cases determines slight alterations in the results. To deny inherent power in the original bioplasm is to deny without reason—to deny as a dogmatist or a bigot might deny; for the production of any formed material without bioplasm is impossible. Why or how bioplasm produces formed material we know not, but I have shown that the bioplasm dies—ceases to be bioplasm, whenever formation occurs—whenever structure is produced. And what are we to under- stand by the nature, or power, or property of living bioplasm? With what is it comparable? With the properties of non-living matter? Clearly not, for do not these belong to the matter itself, whether it be living or dead? Jjwving properties are transferred from one particle to others with the utmost rapidity, but the very same matter may exist with or without its vital properties. By no alteration‘of conditions of which we have any conception can a given portion of matter which has once passed from the living to the dead state be restored to the living condition, and it is intolerable that we should be expected to receive the dictum that the form, properties, and action of living things are to be fully accounted for by the pro- perties of the mere matter which enter into the com- position of their bodies. 19 LECTURE II. Examples of Bioplasm in Tissue—A young Leaf and its Bioplasm—Cartilaye and its Bivplasm— Epithelium and iis Bioplasm—Mucus and its Bio- plasm—Movements of Bioplasm—Origin of new Centres—Bioplasm must be nourished—How Pabu- lum may be brought near to the Bioplasm—Organs for Introducing Food—Distribution of Nourishment —Rapid Growth of Bioplasm in the Adult and in Old Age—Rapid Growth of Bioplasm im Disease. In the present lecture I propose to allude to the characters of bioplasm as far as they can be ascer- tained by low magnifying powers, and I shall allude to several points generally, which will be more particu- larly described in Lecture IV. It will be more con- venient to postpone the consideration in detail of the wonderful phenomena of the bioplasm, until the student is acquainted with general facts more easily understood. Nevertheless those phenomena may be observed by any one well acquainted with the use of the higher powers of the microscope. They are of surpassing interest, although not to be explained by science, or accounted for by philosophy. I shall refer to a few simple textures containing bioplasm. If the student will place the structures alluded to under his microscope, he will be able to verify the few remarks that will be made in this place. 31. Examples of bioplasm in tissue. A young leaf and its bioplasm.—If a leaf bud be examined before any of the green colouring matter has been formed, the colourless bioplasm will be found occupying the cavities or little spaces in the tissue of which the c2 20 EPITHELIUM AND ITS BIOPLASM. embryo leaf consists. The bioplasm is perfectly transparent and looks like pure water. The cavity m which it les has been termed a space or vacuole which was supposed to be occupied by mere passive finid- But the colourless material is living bioplasm, and so important that the walls of the spaces (cellar walls) could not have been formed except by its agency. 32. Cartilage and its biopiasm.—In a piece of eartilage or gristle it is easy to see the little masses of transparent structureless bioplasm, and distinguish these from the firm cartilage material which inter- venes, and which has been formed by them. The structure of cartilage will be again referred to. 33. Epithelium and its biopilasm.—If a little of the soft matter be removed from the inside of the cheek, and examined under a magnifying power of two hundred diameters, it will be found to consist of numerous little particles (elementary parts or cells), every one of which contains in the central part an oval mass of living matter, around which is a firmer material that has been formed by the bioplasm, and was deposited layer within layer. Often very distinct concentric rings may be seen, owing to this mode of deposition. The younger the particles of epithelium* the larger is the mass of soft colourless living bioplasm in proportion to the formed material of which the outer part consists, and which has ceased to manifest vital properties or powers. 34. Mucus and its bioplasm—lIf a little viscid mucus be coughed up and examined under the mi- croscope it will be found to be very transparent, and to exhibit streaky lines here and there. At short dis- tances will be observed oval particles of transparent * Epithelium, from ézi upon, and @4\Xw to sprout, for it used to be supposed that epithelium grew or sprouted from membrane. Epithelium really is formed by bioplasm which sprang from preexisting bioplasm; the bioplasm existed before the membrane and therefore could not have sprung from it. MOVEMENTS OF BIOPLASM. 21 living matter or bioplasm, from which the mucus has been formed. These correspond with the masses of bioplasm of the cartilage and the epithelium, and the mucus with the formed material of these textures only. (See also §§ 79, 80, Lec. IV.) 35. Movements of bioplasm.— The oval masses of bioplasm in the mucus, like those in the tissues before referred to are alive, but the bioplasm being free to move in a soft medium, the remarkable movements ean be actually observed, and may be studied without difficulty with the aid of a ~,th of an inch object glass, magnifying from six to seven hundred diameters as will be explained in Lecture IV. No material can be made artificially, in which such movements as these can be produced. This power of movement is invariably possessed by bioplasm. The rootlets of the plant extend themselves into the soil, because the living matter at their extremities moves onwards from the point already reached. The tree grows upwards against gravity by virtue of the same living power of bioplasm. In every bud, portions of this living matter tend to move away from the spot where they were produced, and stretch upwards or onwards in advance. No tissue of any living animal could be formed unless the portions of bioplasm moved away from one another. Portions of the bioplasm move and place themselves beyond the point already gained. The above are vital movements. (See § 80.) 36. Origin of new centres.—But besides these movements another phenomenon still more remarkable occurs in connection with bioplasm. In the very substance of the living matter itself, one or more spots make their appearance, arising as it were from within. They spring up and grow within the living matter. Absorbing nutrient material they grow and push outwards the bioplasm already existing. Again, new points of bioplasm may arise within these last. So that we may have two or three different centres of 22 BIOPLASM MUST BE NOURISHED. growth, one within the other. The inmost of all is the last produced, and this is often found to be endowed with powers or properties different from those manifested by the bioplasm which preceded it, in which it was devoloped, which it is to replace, and which perhaps is to be entirely destroyed in order that the last, the newly developed bioplasm, may flourish for a time, and then give place to new centres which in their turn will appear within it. These little spots are known as “nuclei.” The spot within the nucleus is the “ nucleolus.”” (See § 85.) 343. Bioplasm must be nourished.—Hvery kind of living matter when it increases is said to be nourished. In order that the act of nutrition may occur it is necessary that the material constituting the pabulum or nutrient matter should be brought very closé to the living matter. A part of the latter then moves towards the non-living pabulum. Bioplasm through- out its life tends to move away from its centre. Its particles seem to be impelled centrifugally towards any nutrient matter that may be near to it. Whether or not the non-living pabulum is taken up and con- verted into the living depends upon a number of circumstances which the living is utterly powerless to occasion, influence, control, or modify. But these external conditions being favourable and the pabulum being very near to the living matter, some of the latter is taken up by the living bioplasm, which com- municates to certain of the non-living constituents its own particular properties or powers. Such essentially is the phenomenon of nutrition, which is universal in the living world, and which in fact consists of the taking up of the non-living matter by living matter and its incorporation with it. The non-living is made to live by the agency of that which is already living. The process of nutrition of an elementary part is more particularly described in Lecture V. 38. How pabulum may be brought near to the bic- ORGANS FOR INTRODUCING FOOD. 23 plasm.—The manner in which the pabulum is brought into very close proximity to the bioplasm, or into actual contact with it is very different in different cases. In man and the higher animals this operation is provided tor by a highly complex apparatus deserving the most attentive study. So important is this to the well-being of the individual that, should any part of its intricate structure be impaired or its action modi- fied in any great degree, serious derangement of the nutritive process results, and structural change of the most important kind in ergans of the highest import- ance to the life of the complex being is occasioned. In the case of the simpler forms of life the pabulum is brought into the immediate vicinity of the bioplasm, so to say by accident. A breath of air, a drop of rain, may contain the pabulum which will provide for the free growth of some of the simplest organisms, which increase and multiply in so short a time. 39. Organs for intreducing food.—In man and the higher animals most important organs minister to the introduction of pabulum into the intestine where multitudes of bioplasm particles are ever ready to take it up and grow and multiply at its expense. The introduction of aliment is not suffered to depend upon our reason and thoughtfulness. If the demand for food be not duly satisfied, the sensation of hunger is experienced, and when this becomes intense, every other desire, every other interest is in abeyance until the demand for food has been satisfied. 40. Distribution of nourishment.—The bioplasm having taken up the nutrient matter from the diges- tive tube undergoes change; a part of it dies, and some of its constituents, dissolved in water, pass into the blood which flows in channels close to it. The apparatus concerned in the distribution of the nutrient matter so dissolved to all parts of the body of man and the higher animals and plants, consists of tubes so communicating that the contained fluid may tra- 24 RAPID GROWTH OF BIOPLASM. verse them freely and return to the same point. This is circulation. In the higher animals and man these tubes and certain organs “connected with them, con- cerned in the pr opulsion of the fiuid, are comprised under the head of circulating organs, and the fluid which continues to circulate in the vessels as long as life lasts is called the nutrient circulating fluid, or the blood. The Heart.—The most important of these organs is the heart, which is a cavity, the walls of which are entirely composed of muscle, alternately becoming, contracted and relaxed sixty or seventy times in a minute, as long as life lasts. When the muscular tissue contracts, the cavity is much reduced in size, and part of its contents are forced out into a vessel continuous withit. The cavity enlarges again during the relaxed state of the muscular walls, and then it receives fluid instead of expelling it. This hollow muscular heart is connected with different sets of tubes or vessels. From one set it receives blood which it drives into the other set of tubes. The part of the heart which receives is called the auricle or receiving cavity, and this opens into the ventricle or propelling cavity. When the latter contracts, the blood is not driven back into the auricle, because some valves between the two cavities are instantly closed, and the whole force of contraction is spent in driving the fluid onwards into the large vessel or artery. Now, in man’s heart, there are two auricles and two ventricles. This double heart is necessary for driving the blood through the vessels of the body generally, and through those of the lungs. The right auricle receives the dark blood from the veins ; it then passes into the right ventricle, by which it is driven to the lungs, where it loses its dark colour from parting with carbonic acid, and acquires a bright red hue from gaining oxygen. After tra- versing the lungs, the blood is received by the left auricle from which it passes to the left ventricle. By RAPID GROWTH OF BIOPLASM IN DISEASE, 25 the contraction of this cavity, the blood is driven through the arteries of the system, and having tra- versed the minute ramifications or capillaries, it reaches the veins, and is at length poured into the right auricle, the point from which we first com- menced to trace the course of the circulation. But in all these highly complex operations a cardinal fact must not be lost sight of, viz., that bioplasm takes up the non-living pabulum and causes it to live, and that portions of this bioplasm, from time to time, undergo change and die, becoming resolved into compounds which did not exist before. The food is not simply dissolved and caused to pass into the blood as would be inferred from the description usually given, but millions of masses of bioplasm live and grow, pass through certain stages, and die, yielding up the products of their death, to be taken up by other bioplasm-particles, situated in the walls of the vessels and in the blood itself. 41. Rapid growth ef bioplasm in the adult and in ola age.— Although therefore for the most part the bioplasm of the tissues of the adult changes very slowly (§ 28), there are parts of the body in every complex animal and in man which, even in extreme old age, contain bioplasm, which grows and changes as fast as it does in early life. In the absorption of the nutritious matter vast multitudes of little naked masses of bioplasm take up, appropriate, and change the constituents of the food. Thus these little masses grow. After having reached a certain size little offsets project from different parts of them, and from time to time become detached. It is in this manner that the masses multiply. 42. Rapid growth of bioplasm in disease.—In disease the restrictions under which bioplasm grows in the tissues are in part removed, and growth takes place as rapidly as, or even more rapidly than it occurs in the case of the bioplasm of the embryo. 26 MICROSCOPICAL PREPARATIONS. This is essentially what takes place in inflammation. The bioplasm takes up pabulum, and multiplies a hundred-fold. In the case of cancer, tubercle, and other “morbid growths,” the bioplasm grows much , faster than healthy bioplasm, and appropriates nu- trient pabulum more readily. 43. Pus corpuseles.—It is through the increased growth and multiplication of normal bioplasm masses that the morbid “pus corpuscle” results. Pus is living bioplasm which grows and increases rapidly. Pus may result from the rapid growth of one mass of bioplasm, and in twenty-four hours, if nutrient matter be freely supplied, from one mass of normal bioplasm thousands of masses of morbid bioplasm or pus may result. Every one of these grows, gives off diverticula, and so the process of multiplication proceeds. It is also by very rapid growth and multiplication of bioplasm that disease germs are produced. These minute particles of bioplasm formed in one individual may pass through the air and gain access to the blood of another, grow, and multiply there, producing an- other case of “‘ disease.” MicroscoricaL PREPARATIONS ILLUSTRATING LECTURE II. No. of diameters magnified. 1. Cartilage, common frog or newt, showing bioplasm and formed matter ae 3c oe «< EU 2. Bioplasm and formed material, vegetable tissue .. 215 3. Cells or elementary parts, cuticle, newt. Old cuticle on surface. Young cuticle beneath Bn. ae alls 4. Cells or elementary parts of capsule ofa seed .. 130 5. Cells or elementary parts of growing seed.. Boe etl, 6. Cuticle from the nose of the mole .. “1 See a) 7. Fat cells with small masses of bioplasm, ne 22) 2d 8. Bioplasm, growing fungus .. Ae 56 oo, 215 9. Bioplasm forming buds or offsets of growing tissue at a very early period of development. Man.. 215 10. Bioplasm of fungus from a rotten apple .. oe) ate 11. Large masses of bioplasm, newt .. 2< vot BS 27 LECTURE III. The Ovum or Egg—Of Development—Interstitial Chan- nels—Vessels—Structures and Organs— Alimentary Canal—Glands for producing Solvent Fluids—The Blood for Nutrition—The Lungs for Respiration— The Liver for making Bile and Sugar, and altering the Blood—The Kidneys for forming and separating Excrementitious Matter—Cutaneous Glands for Se- creting—Temporary Structures for use while the Per- manent Organs are being formed-—Skeleton—The Nervous System — The Muscular System — The Timbs—The Skin with Touch Organs—The Tongue —The Nose—The Kar—The Eye. 44. The Ovum or Egs.—The contents of the bird’s egg are not directly converted into the tissues of the chick, but probably more than nine hundred andninety- nine thousandths of the egg of the bird consist of pabulum upon which the developing embryo is to live. These constituents of the yolk, as well as the albumen or white of the egg, are taken up and changed by the minute speck of bioplasm which is the germ of the growing chick, just as food is taken up and appro- priated by other forms of living bioplasm (§ 40). As soon as vessels are developed, these substances are taken up by bioplasm, just as pabulum from the intestinal canal in after life, and converted into blood. From this blood the various substances out of which the tissues are formed are taken. The won- derful growing point or spot which though so minute is the most important part of the egg, can always be seen if the egg be placed on its side and a portion of the uppermost part of the shell be carefully removed. 28 THE OVUM OR EGG. There is a white circular area, a little more than the eighth of an inch in diameter, which from being sur- rounded by the lightest part of the yolk, is always uppermost as the egg lies. In the centre of this is the minute mass of bioplasm which is the parent of all those from which the tissues are subsequently formed. Now in batrachia (frogs, newts, &c.) and fishes the part of the ovum which corresponds to the great bulk of the egg or the food yolk of the bird is very small, because the pabulum required during development is principally derived from the surrounding fluid, which is filtered by passing through a most delicate fibril- lated tissue, which surrounds the ovum.* In mam- malia the ovum is very minute, and consists almost entirely of bioplasm, which takes part in the formation of the germ. Its nutrient matter is supplied from a soft spongy tissue of the mother, specially formed for it. In this it is embedded. It imbibes its pabu- lum during the early period of its existence. As it grows it derives the substances to nourish it from the mother’s blood (§ 58). The germ is not in any way dependent upon nutrient matter formed with it or soon after it, and inclosed with it in a confined space, as in the case of the eggs of birds, and also in those of the snake, tortoise, and many other members of the reptilia. The mammalian germ is in fact entirely and solely dependent upon the maternal organism for its nutrition. Moreover the eggs of most reptiles and some birds are hatched altogether without the assist- ance of the mother, and in few cases is this a necessary condition of development. The developmental changes proceed quite as regularly and as perfectly when the egg is exposed to artificial heat as when it is incu- * This looks like the white or albumen of the bird’s egg, but it is not albuminous, and consists of very delicate tissue, the meshes of which are occupied by water. It is a structure very like the vitreous humour of the eye. OF DEVELOPMENT. 29 bated by the animal heat developed by the maternal organism. 45. Of development.—At first, however, in all cases the minute particle of simple structureless bio- plasm (§ 11), out of which a complex organism is evolved, gets its nourishment direct from the matter which surrounds it, whether this is enclosed with it from the first in a firm shell or supplied to it as required from the blood of the mother. The fit and proper substances are selected by the living matter which moves towards them (§ 37), takes them into itself, and converts these into more living matter like itself. Thus the primary living mass, from which springs every succeeding bioplast that takes part in the formation of the entire being, increases in size. It divides into two or more, and these grow and divide and subdivide until multitudes result. But as the collection of bioplasts becomes larger by subdivision and growth, it is obvious that the component bio- plasts must be separated from the nutrient food by very unequal distances. Without some special pro- vision this would involve unequal nutrition. The bioplasts apon the outer part or surface being in actual contact with the food, would grow quickly, whilst those towards the centre of the mass would increase very slowly, and would cease to grow at all in consequence of little or no nutrient material reach- ing them. They would be starved and die. Sucha state of irregular growth does actually occur in the case of certain morbid (cancerous) structures. Owing to the circumstance of the irregular distribution of nutriment, in one part growth is most rapid, while in another situation the tissue actually dies from starvation, and is often invaded and consumed by new growth. Ina very small space we may find in such a texture, 1, young actively growing matter; 2, fully formed tissue; 3, decaying texture; and, 30 INTERSTITIAL CHANNELS. 4, the products resulting from changes occurring in tissue long since dead. Interstitial Channels.—But in every embryo and in every normal tissue the equable distribution of nu- trient matter is provided for and the flow regulated. As the growing embryo increases in size, intercom- municating spaces (lacungz) and channels are formed here and there, and along these the fluids adapted for nutrition freely pass and meander in all direc- tions, bathing, it may be, uniformly the growing bioplasts in every part, or distributing amongst them a gradually diminishing quantity of nutrient matter according as the distance from the nutrient surface increases. See Lect. V, § 117. 4G. Vessels.—In the higher animals and in man actual tubes (vessels) are, however, developed for the purpose not only of conveying nutriment long distances from the one part of the body where it is taken up, and distributing it freely and equably to the several tissues and organs, but for removing products re- sulting from decay. Every part of the developing mass receiving its proper supply, growth may be as active or more active in those portions which are situated at the greatest distance from the point of supply than in those quite close to it. The vessels form a system of closed tubes composed of deli- cate membrane. These tubes are continually being traversed as long as life lasts by fluids holding in so- lution or in suspension everything that is required by .the growing tissues which differ so remarkably from one another in structure, chemical composition, and physical and physiological properties. These tubes are everywhere so arranged that the contained fluid “may circulate very rapidly and very freely. In this way every part of the growing mass is irrigated, but the growing tissue is not in contact with the nutrient fluid. The wall of the tube intervenes, but this is usually so very thin that solutions will pass through STRUCTURES AND ORGANS. 31 it very quickly in both directions. And, indeed, a solution of substances adapted for the nutrition of the tissues is continually flowing through the wall of the vessels towards the bioplasm of the several tissues, while substances, resulting from the decay of tissues, also dissolved, flow in an opposite direction from the tissues through the vascular wall into the blood. The blood is driven through the vessels by the pump- like action of the heart into the interior of which the vessels open. (Page 24.) 47. Structures and O@rgans.—As the embryo in- creases in size and advances in development strik- ing differences in character become manifest in diffe- rent parts. Peculiarities of structwre are observable, and the different structures perform very different offices. The vessels in which blood circulates are, however, distributed to them all, but the composition of the blood is altered both as regards what it gives up and what it receives, as it traverses the vessels distributed to the several parts. 48. Alimentary Canal.—In vertebrate animals an important.tube is developed which is set apart for the reception and preparation of the food, and although this is not required during embryonic life, it must be formed so that it may be ready to do its work—to perform its highly important fwnction when the newly formed organism comes into the world. Its charac- teristics in every stage through which it passes during its construction proye to us that the form it was ulti- mately to assume and the work it was to perform were, as it were, anticipated from the first. For months during its gradual formation it fulfilled no useful purpose whatever, and yet change succeeded change in pre-arranged order, until at last highly com- plex structures, adapted for certain definite purposes only, were evolved. The formation of these is com- plete, and they are ready to discharge their function at the time when their activity becomes necessary to 32 GLANDS FOR PRODUCING SOLVENT FLUIDS. the maintenance of the life of the new being under the greatly altered conditions of existence. 49. Glands for producing solvent fiuids.—In this digestive tube or cavity the undissolved food must be acted upon, so that it may be dissolvedin water. The solution thus prepared is to be taken up or absorbed by the blood. Various secreting glands are therefore developed in connection with the digestive tube. These select certain materials from the blood com- mon to the whole body, and convert them into fluids having very special and peculiar properties and endowments, which when fully formed pass away from the gland, being conducted by a tube or duct to different parts of the canal, where they become mixed with the food and exert their peculiar influence. Such are the salivary glands of the mouth, the stomach glands, the intestinal glands, the liver, the pancreas, and several others connected with the in- testine which need not be particularised now—each taking part in a particular but very different ope- ration. The saliva has the property of changing starch into sugar, and in a few seconds. The gastric juice dissolves meat and all forms of fibrin and co- agulated albumen. The pancreas and the liver have to do with the digestion of fatty matter, and the secretions of the intestinal glands exert yet different actions. From the digestive tube nutrient matter is taken up by masses of bioplasm, and by these passed on, as it were, to blood-vessels, as has been already stated in § 40. The newly introduced pabulum is converted into blood by bioplasm, and this blood is driven through the minute vessels (capillaries) im every part of the body. Through the walls of the capillaries, fluid transudes, which is taken up by the bioplasm of the several tissues lying outside the vas- cular canals. In a similar manner it is probable that the bioplasm in the walls of the vessels and the bio- plasm in the blood take up the matters resulting THE BLOOD. 33 from the disintegration of tissues and return them in a modified form to the blood. 50. The Biood.—The blood is the fluid from which the material constituting all the tissues of the body is derived. It exists at avery early period of develop- ment, before the tissues exhibit their structural character or special properties. The food we take is not directly converted into tissue, but into blood. Neither are the substances resulting from the breaking down of tissues at once converted into the materials which are excreted from the body by the lungs, liver, kidneys, skin, and intestines, but into blood. The order of change therefore may be represented thus 1. food; 2. blood; 3. tissue; 4. products of decay ; ». blood; 6. excreted matter. But if we take more food than our body requires, the excess, after having been converted into blood, is excreted without being first converted into tissue. This excess is not only useless, but its excretion may overtax our organs and damage them very seriously, particularly if they are not of large size and in thoroughly good order. x- cess of food is not unfrequently in this way the cause of derangement of certain important organs, particu- larly the liver and kidneys, and may occasion early death. The blood is bemg continually renovated by the conversion of food into it. The food does not pass directly into the blood-vessels, but certain of its constituents are selected and absorbed by the living matter of the walls of the blood-vessels, and by that of the blood itself. In this way the food is changed and converted before it becomes blood. 51. Bioplasm of the Bloed.—The blood is nota mere solution of food matter, but contains many _ livmg particles in suspension, which circulate with it, and grow and multiply, and arrive at matu- rity and die, becoming resolved into matters which are dissolved in the liquid which permeates the walls of the vessels, and is applied to the nutrition of the D 34. RED BLOOD CORPUSCLES. growing tissues. The living particles of the blood vary greatly in size and number, according to the quantity and nature of the food, and a number of circumstances. There exists suspended in the fluid portion of the blood, multitudes of living particles, so minute that they cannot be seen by ordinary magni- fying powers. These play a highly important part in the phenomena ofthe body. I described these minnte particles of bioplasm in 1863.* 52. Red Blood Corpuscles.— Besides the particles of living matter, the blood of all vertebrate animals contains multitudes of small, soft, semi-solid particles of a red colour, which give to blood its characteristic appearance. In health, in warm-blooded vertebrata, these are very numerous, and are known as the red blood corpuscles. The fluid in which these little cor- puscles are suspended is by them as it were much divided, a small portion being smeared over each indi- vidual red blood corpuscle. As these are kept by the propelling power of the heart in continual motion, the equable composition of the blood is maintained, and a small quantity of the fluid portion is smeared upon the wall of the vessel, and upon the bioplasm of the capillary which projects into the cavity, as the red blood corpuscles one after the other are driven into contact with it. So perfect are these arrangements in their working, that irregularities in the distribu- tion of the fluid are corrected or compensated while there exists also provision for ensuring that the general composition of the blood shall remain con- stant, in spite of its undergoing most important changes in every part of its course. 53. Liver for making Bile and altering the Blood. —The liver, unlike the other important secreting organs developed in the embryo, attains functional im- portance at a very early period of life. Long before * “On the Germinal or Living Matter of the Blood.” Trans. Mie. Soc., Dec. 9, 1863. LUNGS FOR RESPIRATION. 30 birth, and long before most of the important tissues of the body exhibit their characteristic structure, some time before the intestine into which the secre- tion of the gland is poured, is fully formed, the liver not only possesses the structure it exhibits perma- nently, but it performs its work, and probably in much the same way as during later periods, when the conditions under which life is carried on are so very different from what they are during development. In short, the liver seems to be formed as a permanent organ almost from the very first, and fulfils two very important functions. By its agency, certain matters are separated from the blood, and converted into two distinct classes of substances, one of which is re- turned to the blood soon after its production, while the other is carried away from the gland and poured into the intestine. The material formed by the liver and returned to the blood is sugar, and that which is carried to the intestine 1s bile, of which part seems to be effete, and at last escapes from the bowel, while part is re-absorbed in an altered state by the intestinal capillaries, and mixed with the blood. 54. Lungs fer respiratien.—In another part of the ’ developing being organs are formed which are des- tined to effect, without a moment’s interruption, most important changes in the blood, from the instant after birth until death. These organs are the lungs, and as the blood traverses the capillaries it takes up oxygen and gives off carbonic acid and other constituents. 55. The Kidneys for secreting.—The /idneys con- tain bioplasm which selects various matters from the blood. It undergoes change, and becomes re- solved into certain constituents, which pass away from the body altogether. These glands attain their perfect form slowly, and are preceded by temporary organs. 56. Cutaneous glands.—Glands are also found in connection with the skin, whose office it is to D2 36 TEMPORARY ORGANS. remove from the blood certain deleterious matters, and discharge them in the form of perspiration and sebaceous oily matter. 54. These organs forthe most part inactive during embryonic life — But to the embryo, with the exception of the liver, the above organs are comparatively useless. They are being formed for work, but are as yet in- capable of work. Nevertheless, the work that will in the future be discharged by them must be performed somehow. Food must be introduced though the digestive organs cannot be used, oxygen must pass into, and carbonic acid out of, the blood, though the lungs cannot act: and various deleterious excre- mentitious materials must be got rid of, though the glands being formed for this special purpose are inoperative. 58. Temporary organs.—There is an arrangement specially to fulfil these duties for the time. Various temporary structures which are discarded at birth, or are gradually destroyed and removed after birth, perform, and in a most perfect manner, the highly essential operations which are afterwards carried out in a very different way. From the blood of the mother is taken the nutrient matter from which the blood found in the vessels of the growing embryo is prepared, and into the maternal blood some of the products of deeay are discharged. It likewise gives oxygen to the embryo’s nutrient fluid, and receives from it carbonic acid, which is ultimately excreted by the maternal respiratory apparatus. 59. The Skeleton.—The firm internal bony skeleton. characteristic of all vertebrate animals, and which supports all the other tissues of the body, is developed at a time when no such support is required. When the skeleton is first formed, it is as soft as the soft tissues, and it only gradually acquires firmness as the form of the several bones manifests itself. In the soft state it is quite useless for the purposes for which NERVOUS TISSUES. oe it is required, and a further important change is necessary. The soft transparent tissue, of which it is in great part composed, becomes infiltrated with earthy matter, consisting principally of phosphate of lime and magnesia, and this process continues in progress even until after the animal has attained its perfect form. But the bone, which is first produced, is only a temporary siructure, and far too weak and brittle for the requirements; for, besides hardness, bone must possess elasticity in some degree, so that it may stand a sudden blow without breaking. The whole of the bone first. formed is, in fact, removed, and gradually replaced by a firmer, harder, much stronger, and more elastic and more permanent tissue, very different in structure from that which preceded it. But this more perfect type of bone tissue could not have been developed at the first. Its production involved a number of preliminary changes useless to the economy until the whole series was fully completed. Nor from the structural cha- racters of the early tissue would it have been possible to premise the structure assumed by the permanent bone. Here, as in so many other cases, we see highly elaborate and complex structure anticipated, as it were, at a time when its actual production would have been impossible. It is therefore certain, that the most thorough knowledge of the properties of the matter of a living being would not enable us to form any conception of the form the tissues were ultimately to take, or the office they were to discharge. 60. Nervous tissues.—The nervous tissue is de- veloped pari passw with many other textures of the body. And of all the tissues it undergoes the most remarkable progressive changes. The relation of some of the most important parts of the nervous system is being continually altered, and yet without any derangement of function in any portion of it. Nerve tissue comes into very close relationship with 38 THE SKIN. many other textures, and reaches the utmost confines of the system. Its structure is elaborate, and its work in some cases never ceases for a moment as long as life lasts. Unlike every other tissue in the body, the nervous tissue exhibits uninterrupted con- tinuity of texture. There is not a thread in any part of the nervous system the tissue of which is not con- nected with the nerve tissue of other parts,—which is quite disjoined from other threads and nerve matter. Gi. The muscular tissue is to be detected at a very early period, and two different kinds of tissue having contractile property can be distinguished in man and the higher animals. The movements of one being under control of the will, through the interven- tion of nerve tissue is termed voluntary muscle, the other, although equally under nervous control, is not directly influenced by the will, and indeed contracts without our being conscious. This is called organic or involuntary muscle. Such a division is, however, not strictly accurate, and it is better to speak of these two kinds of muscular tissue respectively as the striped or transversely striated muscle and the wnstriped muscle. Although examples of the first are usually under voluntary control, and therefore properly termed voluntary muscle, instances are not wanting of striped or transversely striated muscle which is not under the influence of the will. At an early period of de- velopment the striped muscle resembles the non- striated in general appearances as will be described when muscular tissue comes under consideration. 62. The skin.—As would be. supposed, a texture composed of so many different tissues as the skin and performing so many important functions, acquires its perfect development but slowly. Connected with the cutaneous system are nails, hairs, and in many of the lower animals horny structures. The glands for the secretion of the sweat open upon the surface of the skin, and the sebaceous glands secreting oily matter MUCOUS MEMBRANE. 39 near the mouth of the follicle in which the hair is lodged. Lastly, in some parts of the skin, par- ticularly the tips of the fingers, the lips, and the tip of the tongue, a beautifully delicate apparatus connected with the sense of touch is formed. 63. Mucous membrane.—Closely allied to the skin in structure, and indeed continuous with it, is a sort of internal skin called mucous membrane, which lines the digestive apparatus from one end to the other, and also the respiratory organs. The mncous mem- brane is modified in structure in every part of its course according to the offices it has to discharge. In some situations the surface is hard and even horny, while in others it is soft like velvet. Almost dry and rigid in some places, in others consisting of glands packed closely together and constantly secret- ing an enormous quantity of fluid. Again, instead of being a secreting surface, a considerable extent is modified to form a highly efficient absorbing apparatus. Besides the many tissues and organs already enumerated, several very highly elaborate structures are gradually formed which cannot come into use at all until after birth. The development of these con- tinues to advance for some time, and not only is it doubtful if they attain their most perfect condition before the adult period of life is reached, but it is certain that some of them continue to improve for many years afterwards. 64. Organ of smeli.— The organ of smell is in its structure much simpler than the other organs of special sense, but the arrangement of the nervous apparatus is very beautiful. The nerves come quite to the surface, and it is probable that odoriferous par- ticles come into actual contact with nerve tissue. The olfactory mucous membrane in very young animals is a tissue in which the ultimate ramifications of nerve 40 ORGAN OF TASTE. fibres and their relation to other tissue elements may be studied with success. 65. Organ of taste—The tongue is a highly com- plex organ ; not only is it exceedingly sensitive as an organ of touch and taste, but the muscles, of which the substance of the tongue is entirely composed, are re- markable for the delicacy and perfection of their move- ments, and for the wonderfully rapid and varied con- tractions executed by them, which are purely volun- tary. The movements of the tongue so immediately respond to the will that they almost seem to represent the undulations ofthe mind. By its changes in form, at the same time that a current of air is made to traverse the vocal organ, by the action of other muscles, whose contractions are harmonised with the lingual moye- ments, not only may ideas be expressed in words and rendered evident to others almost as fast as they are formed, but the sounds may be so accentuated as to convey to the understanding of others far more than is indicated by the mere words themselves. 66. Organ of hearing.—The ear is developed at the time of birth, but it continues to improve eyen for many years afterwards. Its structure is most elabo- rate, and the arrangement of every part is such that it is not possible to explain its construction by any known laws. To attribute the formation of so com- plex an organ, consisting of so many elaborate, inter- dependent, and mutually adapted parts to evolution is mere trifling with words. A few years ago it would have been said that its development was due to the gradual differentiation of the originally homo- geneous—but such phrases are sad examples ef what by worldly-minded persons would be termed imposi- tion. Statements of this kind would certainly justify the inference of clever, if ungenerous critics, that the authorities who employ them must have a supreme contempt for the people whom they profess to be ORGAN OF SIGHT. Al very anxious to teach, but whom they are really trying to astonish only. 6%. Organ of sight.—The eye, the result of a long series of the most marvellous developmental changes, at last appears an organ, the mere structure of the nervous part of which has not even yet been thoroughly elucidated. There is not a portion of the eye that will not excite admiration on the part of the student who investigates it. The adaptation of every struc- ture to the work it will have to perform is most remarkable, and when we consider that this organ, use- less without light and formed for light, was produced in utter darkness, it is difficult indeed to understand how anyone can venture to adopt the belief that the various arrangements of tissues are due to the opera- tion of external circumstances, and the properties of the mere matter of the body. From the very first the perfect form the organ was to assume must, as it were, have been determined and foreseen. To say that the fully formed eye existed potentially in the masses of bioplasm, from which its tissues were formed, neither indicates scientific knowledge, nor a love of accuracy, nor candour. The very matter was absent, out of which these tissues were to be formed, and yet their formation was prepared for, and, as it were, antici- pated from the very first. All the early and most im- portant changes in the development of an eye cannot be attributed to the operation of any external condi- tions whatever. They must be due to forces or powers acting from within, and influencing the matter con- stituting the bioplasm at the time, and these forces and powers exhibit nothing whatever in common with any known forces, properties, or powers of non-living matter. Mr. Darwin remarks that the telescope ‘‘ has been perfected by the long-continued efforts of the highest human intellect” ; and, he says, we “ naturally infer (!) that the eye has been formed by a somewhat anala- 42 ENDOWMENTS OF BLOPLASTS gous process.” But natural inferences and analogical arguments of this kind do not forward natural know- ledge. The perfection of an optical instrument by experiments conducted by man in daylight surely throws marvellously little light upon the question of the formation of an eye in darkness, altogether without man’s agency. We have seen that, as development proceeds, the original mass of simple living matter gives rise, by growth. and subdivision, to multitudes of descendants, which succeed one another in regular order until at last a number of bioplasts result, which take part in the formation of tissues differing remarkably from one another in properties, and organs which per- form very different kinds of work, duty, or function. But all the different tissues and organs are supplied by vessels and all nourished by the same blood. By the agency of bioplasm, however, very different sub- stances are produced, although the elements of all are derived from the same blood. Thus, saliva, gastric juice, bile, and urine have very few properties in common; they are secretions, having very different chemical composition and properties, and perform very different offices. Yet they are all formed from the blood by different kinds of living matter. It is very remarkable that all these bioplasts which have resulted by descent from the same original mass should possess endowments as different from those of the original parents of them all as they are from one another. No adequate explanation has ever been given of _ this fact. It will be found upon examination that all the explanations that have been offered only amount to statements of the fact itself in a somewhat round- about way. Nor can the formation of tissue be ade- quately accounted for. Form and structure result from the formless and structureless, but to attribute LIVING AND NON-LIVING. 43 such phenomena to what has been called “ diffe- rentiation,” is simply degrading science. We are quite ignorant of the exact nature of the changes that occur, but we do know that the bioplasm lives, and that the tissue formed by it does not live. We shall see that the distinction between the matter which is actually living and that which is not living is a cardinal fact of very great importance. This indeed appears to me to form the very starting point of physiology. Without recognising the distinction between the living and the non-living, all discussion concerning the phenomena of living beings will only lead to vague and contradictory conclusions, and the use of terms and phrases which perplex the student instead of helping him to learn. LECTURE IV. Process of Investiqation—Microscopic Characters of Bioplasm—Mode of Growth of Bioplasm of a simple Vegetable Tissuwe—Sugar Fungus—Bioplasm of Animal Tissue—Hatremity of Tuft of Placenta— Bioplasm of Hair—Bioplasm of Ameba—Bioplasm of Mucus—Movement of Bioplasm—lIrritability and Contractility — Molecular Machinery” — Bioplasm constituting new Centres, or Nuclei and Nucleoh— Production of Formed Material—Structure of a Spore of Mildew—Growth—How is the new Matter added 2—Importance of the Changes. 68. Process of Investigation.—In order to dis- tinguish the invariably transparent lving matter or bioplasm from the frequently transparent formed material, it is necessary to pursue a particular method of investigation, which I have fully described else- where.* The value of this process depends upon the fact that all bioplasm is coloured red by an ammoniacal solution of carmine, while all formed material, not- withstanding it has been traversed by the alkaline coloured fluid, remains perfectly colourless. In prac- tice, certain precautions are necessary, and the density and composition of the colouring fluid must be slightly varied in special cases. But it is necessary that I should state distinctly that, if the process be properly conducted, every kind of living or germinal matter or bioplasm receives and fives the colour, while no kind of formed material known is stained under the same circumstances. I shall have to direct attention * « How to Work with the Microscope.” 4th edition. PROCESS OF INVESTIGATION. 45 to the fact, that the proportion of bioplasm in the same tissue varies at different ages, and that in many different forms of disease the morbid change essen- tially depends upon a considerable increase in the amount of bioplasm. These facts are most positively demonstrated in specimens prepared according to the method described. Moreover, I shall, by the aid of this mode of investigation, be able to show where the bioplasm ceases and the formed material commences, and in some instances, to distinguish which part of a mass of bioplasm was first and which last formed. The action of the carmine fluid upon the bioplasm is well illustrated by a well-prepared specimen of cartilage of the frog or newt. The cartilage tissue, matria, or formed material is left perfectly colourless, and although it consists of a firm, and not very per- meable material, it has been freely traversed by the carmine fluid. The rapidity with which a com- paratively thick layer of the formed material may be traversed by the dark red solution is very remark- able. To illustrate this fact, a few cells may be taken from the liver of a mouse recently killed. The carmine fluid may be allowed just to pass over the cells, and the excess at once washed away with a little weak glycerine. The whole operation can be performed in less than half a minute,-and yet the bioplasm of every cell, in this case called the nucleus, will be coloured bright red, while the outer formed part will be left colourless and unchanged. The formed material in this instance consists of a thick layer of soft matter, which, however, has been freely traversed in the course of a few seconds by a fluid which contains glycerine, and is of higher specific gravity than blood-serum.* This enables us to form some idea of * The fluid which I use in the preparation of my specimens has the following composition :—Caimine, 10 grains; strong liquor ammonia, = drachm; rectified spirit, + ounce; Price’s glycerine, 2 ounces; distilled water, 2 ounces. The carmine 46 COLOUR NOT DUE TO MERE TINTING. the great rapidity with which nutrient fluid passes through the tissue or formed material towards the bioplasm or living matter of the cell or elementary part during life. Even the firm and resisting matrix of cartilage is readily permeated by the carmine fluid without being stained in the slightest degree, while the masses of bioplasm are deeply tinged. G9. Colour not due to mere tinting.—The effect produced is very different from the mere tinting which results from soaking tissues or other bodies in coloured fluids. The staining of the bioplasm depends upon altogether different circumstances, and from it we learn highly important facts. Of course every kind of matter may be tinted,—rag, paper, wood, silk, bone, teeth, shell, and almost every formed matter in nature may be coloured bright red by being soaked in certain coloured fluids. As formed material of any kind can thus be dyed, some observers with- out paying the least attention to the observations which have been made, and without even looking at the specimens and drawings with which my investi- gations haye been illustrated, have hastily inferred that by carelessly steeping tissues in various colour- ing fluids, all the advantages afforded by the use of an ammoniacal solution of carmine can be gained. I cannot discuss the matter in this place, and shall content myself with directing attention to the evi- dence adduced. The ridiculous objections that have been advanced even by persons in positions of autho- rity may be replied to by specimens anyone can make for himself with a little trouble, and by the confirma- tory researches of observers who have not already com- mitted themselves to doctrines concerning the nature of the phenomena of living beings which are incom- may be increased to 15 grainsif it is desired to stain soft tissues very quickly. In some cases it is necessary to adda little water, and in others more alcohol must be added in order to make the solution permeate the tissue freely. MICROSCOPIC CHARACTERS OF BIOPLASM. 47 patible with well-authenticated facts of nature, and calculated only to mislead. 470. Microscopic characters of Bioplasm.—The characters of bioplasm may be studied in the lowest organisms in existence and in plants, as well as in man and the higher animals. Being so very trans- parent and often embedded in dark and more or less opaque tissue, bioplasm has often been overlooked and has been mistaken for mere passive fluid occupy- img a space or vacuole in the tissue. We shall have many opportunities of studying it, but it may be well to repeat that bioplasm or living matter is, as far as can be ascertained by examination with the highest powers, perfectly structureless. It exhibits the same characters at every period of existence, and in every living organism. Gi. Bioplasm of sugar fungus.—The bioplasm of the thallus of the growing sugar fungus exists in considerable quantity, and is well adapted for exami- nation. It may be found in abundance in mouldy jam, and it may be stained without much difficulty. The growing extremity of the branch is rounded, and here the process of growth is going on with great activity ; new living pabulum is being converted into living bioplasm with great rapidity. When the ope- ration of staining has been conducted successfully, these growing extremities will be found to be much more deeply stained than the rest of the bioplasm. 42. Bioplasm of tuft of placenta.—A correspond- ing fact may be demonstrated if one of the little tufts of the placenta (a temporary organ of the embryo by which the nutrient matter is separated from the maternal blood, and which also effects the necessary changes as regards oxygen and carbonic acid) is sub- mitted to examination. At the extreme end of each tuft is a collection of bioplasts which is intensely stained by the carmine fluid. Behind this, and growing towards it, is the vascular loop; but as the 48 VITAL POWER. tufts grow, the mass of formless, structureless bio- plasm at the end of each moves onwards, the vessels being developed in its rear. This formless living matter moves forwards, burrowing, as it were, into the nutrient pabulum, some of which it takes up as it moves on. Itis not pushed from behind, but it moves forwards of its own accord. In a similar man- ner the advancing fungus bores its way into the material upon which it feeds, and the root filament insinuates itself into interstices between the particles of the soil, where it finds the pabulum for its nutri- tion. 42. Bioplasm of the hair.—In the hair the bioplasm grows and multiplies at the base or bulb, pushing the firm and already formed tissue before it. The bio- plasm of the root of a plant increases at the extremity of a filament which it spins off, as it were, behind it; in the case of the hair, on the other hand, the tissue already formed is pushed on by the production of new texture in its rear. The extremity of the hair is its oldest part, and nearest to its root is the tissue which was most recently formed from pabulum absorbed from the blood. 434. Vital power.— But whether bioplasm moves on in its entirety, or, advancing from a fixed point, forms a filament, a tube, or other structure which accumu- lates behind it, or remains stationary itself, while the products of formation are forced onwards in one direction, or outwards in all, the nature of the force exerted is the same, and due to the marvellous power which one part of a living mass possesses of moving in advance of other portions of the same, as may be actually seen to occur in the humble ameeba, in the mucus or in the white blood-corpuscle from man’s organism, as well as in the pus-corpuscle formed in disease. 45. Ameeba.—Among the simplest living things known to us are the amcebe, which might be almost described as animate masses of perfectly transparent BIOPLASM IN DIFFERENT ORGANS AND TISSUES. 4% movirg matter. Amocbe can be obtained for exami- nation by placing a small fragment of animal or vege- table matter in a little water in a wine-glass, and leaving it in the light part of a warm room fora few days. Ihave found it convenient to introduce a few filaments of cotton wool into the water. The amoebe collect amongst the fibres, which prevent them from being crushed by the pressure of the thin glass cover. The delicate material of which these simple creatures are composed exhibits no indications of actual structure, although it is darker and more granular in some parts than in others. 436. Bioplasm in different organs and tissues.— The bioplasm of all organisms, and of the tissues and organs of each organism, exhibits precisely the same characters. It lives, and grows, and forms in the same way, although the conditions under which the phenomena of life, growth, and formation are carried on differ very much in respect of different kinds of living matter. A temperature at which one kind will live and grow actively will be fatal to many other kinds. So, too, as regards pabulum—substances which are appropriated by one form of bioplasm will act as a poison to another. But the way in which the bioplasm moves, divides and subdivides, grows, and undergoes conversion into tissue, is the same in all. Many remarkable differences in the structure, properties, action, and character of the things that are formed are associated with close similarity, if not actual identity, of composition of the matter that forms them. These differences cannot, therefore, be attributed to the properties of the elements, to physical forces, chemical affinities, or to characters which we can ascertain or estimate by physical examination, but they must be referred to a difference in power which is inherited from pre-existing bioplasm, which we can- not isolate, but which it would be quite unreasonable to ignore. E 50 MOVEMENTS OF BIOPLASM. "3. Movements of bioplasm.—One characteristic of. every kind of living matter is spontaneous movement. This, unlike the movement of any kind of non-living matter yet discovered, occurs in all directions, and seems to depend upon changes in the matter itself, rather than upon impulses communicated to the par- ticles from without. I have been able to watch the movements of small amcebe, which multiplied freely without first reaching the size of the ordinary indi- viduals. I have represented the appearance under a magnifying power of 5,000 diameters of some of the most minute amoebe I have been able to discover. Several of these were less than ;5¢555th of an inch in diameter, and yet were in a state of most active movement. The alteration in form was very rapid, and the different tints in the different parts of the moving mass, resulting from alterations in thickness, were most distinctly observed. In these movements one part seemed, as it were, tc pass through other parts, while the whole mass moved now in one, now in another direction, and movements in different parts of the mass occurred in directions different from that in which the whole was moving. What movements in lifeless matter can be compared with these ? 48. Changes ending in formation of a capsule. The movements above described continue as long as the external conditions remain favourable; but, if these alter and the amceba be exposed to the influence of unfavourable circumstances—as altered pabulum, cold, &c.—the movements become very slow, and at last cease altogether. The organism becomes spherical, and the trace of soft formed material upon the surface increases until a firm protective covering, envelope, or cell-wall, results. In this way, the life of the bioplasm is preserved until the return of fayvour- able conditions, when the living matter emerges from its prison, grows, and soon gives rise to a colony of MUCUS CORPUSCLE. iL new amcebz, which exhibit the characteristic move- ments. 79. Mucus Corpusele.—Hvery one knows that upon the surface of the mucous membrane of the air- passages, even in health, there is a small quantity of a soft viscid matter generally termed mucus. This mucus, said to be secreted by the mucous membrane, contains certain oval or spherical bodies or corpuscles, which are transparent and granular. From the changes of form which take place in them, it is cer- tain that the matter of which they are composed is almost diffluent. These corpuscles are mucus corpu- scles, but they have no cell-wall. They are separated from each other by, and are embedded in, a more or less transparent, viscid, tenacious substance formed by the corpuscles themselves, and termed mucus. 80. Its vital movements.—No language could con- vey a correct idea of the changes which may be seen to take place in the form of a living mucus or pus corpuscle or white blood-corpuscle; every part of the substance of the body exhibits distinct alterations within a few seconds. The material which was in one part may move to another part. Not only does the position of the component particles alter with respect to one another, but it never remains the same. There is no mere alternation of movements as in mus- cular contraction. Were it possible to take hundreds of photographs at the briefest intervals, no two would be exactly alike, nor would they exhibit different gradations of the same change; nor is it possible to represent the movements with any degree of accuracy by drawings, because the outline is changing in many parts at the same moment. I have seen an entire corpuscle move onwards in one definite direction for a distance equal to its own length or more. Pro- trusions would occur principally at one end, and the general mass would gradually follow. Again, pro- trusions would take place in the same direction, and E2 2 OF THE MOLECULES OF BIOPLASM, slowly the remainder of the corpuscle would be drawn onwards, until the whole had moved from the place it originally occupied, and advanced onwards for a short distance in the mucus in which it was embedded. From the first protrusions smaller pro- trusions very often occur, and these gradually become pear-shaped, remaining attached by a narrow stem, and in a few seconds perhaps again become absorbed into the general mass. From time to time, however, some of the small spherical portions are detached from the parent mass, and become independent masses of bioplasm, which grow until they become ordinary ‘‘mucus corpuscles.” Are these phenomena, I would ask, at all like any known to occur in lifeless material ? $1. Of the melecules—The component molecules evidently alter their positions in a most remarkable manner. One molecule may move in advance of another, or round another. A portion may moye into another portion. A bulging may occur at one point of the circumference, or at ten or twenty dif- ferent points at the same moment. The moving power evidently resides in every particle of the very transparent, invariably colourless, and apparently structureless matter. By the very highest powers only an indication as if of minute spherical particles can be discerned. Because “molecules”? have been seen in some of the masses of moving matter, the motion has been attributed to these visible particles. It is true the molecules do move, but the living trans- parent material in which they are situated can be seen to move away from the general mass, and into this extended portion the molecules or granules then pass. The perfectly transparent matter moves first, and the molecules flow into it or are moved with it. The movements cannot, therefore, be ordinary mole- cular movements. It has been said that the move- ments may result from diffusion, but what diffusion TRRITABILITY—CONTRACTILITY. 53 or other movements with which we are acquainted at all resembles these? Observers have ascribed the motion to a difference in density of different parts of the mass, but who has been able to produce such movements by preparing fluids of different density ? But further, in the case of bioplasm or living matter, these supposed fluids of different density in some un- explained way make themselves and in some undis- covered manner retain their differences in density ! $2. Irritability —Contractility—Nor is it any ex- planation of the movements to attribute them to inherent “irritability,” unless we can show in what this irritability essentially consists. Some authorities dismiss the matter by saying that the movements depend upon the property of “ contractility,’ but the movements cf bioplasm are totally distinct from “ con- tractility,” such as is manifested by muscular tissue. These remarkable movements take place in every direction, and every movement differs from the rest, while in muscular contraction there is a constant repetition of changes occurring alternately in direc- tions at right angles to one another. Hence, if the movements in question be due to contractility, it is necessary to admit two very different kinds of con- tractile property, which are not of the same nature and not due to like cireumstances.* S3. Movements in the bioplasm of piants.— The movements in the mucus corpuscle and in the ameba, are of the same nature as those which occur in the bioplasm of many plants, as is easily observed in the cells of the leaves of the vallisneria or the anacharis, in the chara, and in the hairs of the flower of Tra- descantia ; and the appearance of the living matter under very high powers is precisely the same in all cases. $4. Movements in morbid bioplasm.—Similar * See my paper “On Contractility as distinguished from purely vital movements.” —‘ Trans. Mic. Soc.,” 1866. 54 BIOPLASM CONSTITUTING NEW CENTRES. movements certainly occur, in the white blood cor- puscle and in the lymph corpuscle, as well as in pus, and in cancer, and in every kind of living matter in health and in disease, though the movement is not in all cases sufficiently active to be easily detected. In some instances the movements continue for many hours after the living matter has been removed from the surface upon which it grew. In other cases, and we shall not be surprised that this should be so in the higher animals, death occurs the instant the con- ditions under which the living matter exists are but slightly modified. In many instances no moyements can be seen, but the evidence of their occurrence is almost as decided as if they were visible, for we demonstrate certain results which cannot be explained unless such movements as those referred to have taken place. T have often tried to persuade the physicist, who has so long prophesied the existence of molecular machinery in living beings, to seek for it in the ‘colourless, structureless,’ bioplasm. But he con- tents himself with asserting that such machinery exists, although he cannot see it or make it evident to himself or others. 85. Bioplasm constituting new centres.—Nuclei and nucleoli.—In many masses of bioplasm a smaller spherical portion, often appearing to be a mere point, is observed. As already mentioned in 36 §, this is known as the nucleus. In some cases this divides before the division of the parent mass takes place. The division of the nucleus is not, however, necessary to the division of the surrounding bioplasm, as was formerly supposed, for division takes place in cases in which no nuclei exist. Moreover it frequently hap- pens that one or more of these smaller spots or spherical masses (nuclei) may appear in the substance of the bioplasm, ajter a portion has been detached from the parent mass. These are new centres composed NUCLEI AND NUCLEOLI DO NOT PRODUCE MATERIAL. 55 of living bioplasm. Within them a second series (nucleoli) is sometimes produced. Marvellous powers have been attributed to nuclei and nucleoli, and by many they are supposed to be the agents alone con- cerned in the processes of multiplication and reproduc- tion. These bodies are always more intensely coloured by alkaline colouring matters than the other parts of the living matter or bioplasm, a fact which is alone sufficient to show the difference between a true nucleus or new centre, and an oil globule, which has often been wrongly termed a nucleus or a nucleolus. In certain eases it would appear that as the process of formation of new centres, one within the other, proceeds, new powers are acquired, or, if we suppose that all pos- sessed the same powers, those masges only which were last produced retain them, and manifest them when placed under favourable conditions. 86. Nuclei and nucleoli de not produce formed material Although nuclei and nucleoli are bioplasm, they do not undergo conversion into formed material. Under certain conditions the nucleus may increase, and exhibit all the phenomena of ordinary bioplasm— _ new nuclei may be developed within it, new nucleoli within them; so that ordinary bioplasm may become formed material, while its “nucleus” grows larger and becomes ordinary bioplasm. The original nu- cleolus then becomes the nucleus, and new nucleoli originate and make their appearance in what was the original nucleolus. The whole process consists of evolution from centres, and the production of new centres within pre-existing centres. Zones of colour, of different intensity, are often observed in a young elementary part coloured by carmine; the outermost or oldest, or that part which is losing its vital power, and becoming converted into formed material, beg very slightly coloured,—the most central part, or the nucleus, although furthest from the colowring solution, exhibiting the greatest intensity of colour. 56 BICPLASM DESTITUTE OF NUCLEI. 87. Biopiasm destitute of nuclei—Bioplasm in a comparatively quiescent state is not unfrequently entirely destitute of nuclei, but these bodies some- times make their appearance if the mass be more freely supplied with nutrient matter. This fact may be noticed in the case of the connective tissue cor- puscles, and the masses of bioplasm connected with the walls of vessels, nerves, muscular tissue, epithe- lium, &c., which often exhibit no nuclei (or according to some, nucleoli); but soon after these tissues have been supplied with an increased quantity of pabulum, as I have shown is the case in all fevers and in- flammations, several small nuclei make their ap- pearance in different parts of the bioplasm. S88. Mode of origin of nuclei. So far from nucle: being formed first and the other elements of the elementary part afterwards, deposited around them, as used to be taught, they make their appearance in the substance of a pre-existing mass of bioplasm, as has been already stated. The true nucleus and nucleolus are not composed of special constituents differing from the bioplasm in chemical composition, nor do they perform any special operations. Small oil-glo- bules, which invariably result from post-mortem change in any form of bioplasm matter, have often been mistaken for nuclei and nucleoli, but these terms if employed at all should be restricted to the new centres of living matter referred to. 89%. Production of formed material from bioplasm. —We have now to consider the manner in which the formed material is produced from the clear, trans- parent structureless bioplasm,—and this is a most in- teresting inquiry, involving questions of fundamental importance. It has been shown that the amoeba may become surrounded by a capsule (§ 78), and the outer part of a mucus corpuscle become firmer than bioplasm, so as to form a “cell wall” to the oval mass of living matter. This alteration is probably de- STRUCTURE OF A SPORE OF MILDEW. 57 pendent in great measure upon change in the external conditions. When these are favourable, the bioplasm of the amceba and the mucus corpuscle grows very fast and multiplies rapidly, but when the external condi- tions are unfavourable, and the supply of pabulum very limited, the bioplasm ceases to increase rapidly, and becomes changed upon the surface ; a firm mate- rial being produced which protects the living matter within from destruction, but which renders its free movement impossible. Under such circumstances, the so-called mucus corpuscle may assume the cha- racters of an epithelial cell. But the growth of bioplasm and the production of the formed material can be so well studied in the lower fungi, that I shall venture to draw attention to the phenomena as they occur in a specimen of this lowly organism before alluding to the change as it occurs in man and animals. 90. Structure of a spore of mildew.—If one of the simplest structures—the microscopic sporule, which is so light that it may be wafted long distances by ‘currents of air—be examined, we shall find that it is not the same in every part. It consists externally of a delicate transparent, glass-like texture, and within of a material having a very faintly granular ap- pearance. In order to demonstrate this fact, a little ordinary mildew dust, which is one of the lowest forms of existence, may be examined. The little round bodies which compose it are comparatively large, and well suited for investigation. They may be studied in glycerine under a twelfth of an inch object glass. Each of these corresponds to a single cell or elementary part of the more complex tissues. It has a tolerably thick well-defined outline, while the in- terior is perfectly transparent. When this transparent matter is expressed and placed under very high magni- fying powers, numerous very minute particles like dots will be observed. Here then are two kinds of ma- 58 CHANGE IN THE SPORE. terial, the one situated externally, firm, glass like, and arranged so as to form an investing membrane closed at all points ; the other lying within, soft, and exhibiting no form or structure whatever. 91. Change in the spore.—If one of these spores fails upon a moist surface where the conditions favour- able for its development are present, it soon undergoes remarkable changes, and abundant growth occurs, so that by the germination of this one minute particle many hundred times its weight of material may result in a very short time, and every portion of the newly formed bioplasm is itself capable of further growth. The changes which occur are of exceeding interest and worthy of the most attentive study. The facts which we shall learn cannot fail to imfluence our general conclusions concerning the nature of the process of growth as it occurs in all living things in health and disease, while at the same time they serve to impress upon us forcibly the amazing dif- ference between growth, as it occurs even in this simple organism, and the mere increase in size which the crystal undergoes, and which has been very wrongly termed growth. 92. Growth of the bioplasm.—Next a new change is observed at one point in the membrane. A small orifice is seen, through which a little of the granular contents of the capsule, covered by a thin layer of the inner part of the membrane, makes its way, and thus a small pear-shaped nodule is formed which projects through the external membrane. This then grows very quickly, and soon forms a sort of process or outgrowth, still connected with the origmal mass _ of bioplasm by avery thin pedicle. Growth continues with considerable rapidity, and soon a new oval spore like the original one results. These facts may be de- monstrated in the rapid multiplication of the yeast- cells in ordinary fermentation. The point of attach- ment becomes less and less, until at last it is completely ANOTHER KIND OF GROWTH. 59 separated, and the bud or offset becomes a free and in- dependent particle, exactly resembling that from which it sprung (except that it is smaller), and capable of growing and giving rise to new individuals like itself, by a repetition of the process by which it was formed. 93. Another kind of growth.—The above is one way in which the particles may multiply, but there are others. In one of these, too, an orifice forms in the membrane of the particle of mildew, and a little of the soft transparent material escapes, but it does not separate as in the first mstance; it remains in connexion with the mass, and grows out into a narrow thread-like process. A long undulating stem gradually results, from various parts of which new buds proceed which grow, and branch like the original one, and sometimes with astonishing rapidity. At first the membrane or formed material of these branches is extremely thin, but it gradually becomes thickened by the deposition of new formed material within, until it acquires considerable firmness, and at the same time it increases in breadth. If the conditions cease to be favourable to growth, the branches cease to extend, and the membranous protective covering acquires increased thickness. Within the sheath is found the transparent matter, from which a number of little spherical bodies or very minute growing particles like those observed within the spherical spore may be obtained. 94. Increase of bioplasm and preduction of formed material These two processes—the extension of bioplasm and the production of formed material— occur under different and often opposite conditions ; the circumstances favourable to the rapid increase of bioplasm being unfavourable to the production of formed material, and vice versd, so that an abundant supply of pabulum is associated with rapid growth of the bioplasm, a scanty supply with the production of formed material. The former is a very rapid process, 60 DEATH OF THE MILDEW. the latter a slow one. Jn a few hours bioplasm may multiply itself a hundredfold, but days or weeks may be required for the formed material to double in amount. If, after rapid growth from exposure to favourable Condakions, the bioplasm be brought under the influence of adverse circumstances, ie formed material cradually increases in ‘iene At the same time the amount of bioplasm becomes less and less, for it undergoes conversion into the formed ma- terial. The latter, therefore, becomes thickened by deposition, layer within layer. At last a mere speck of bioplasm may remain, surrounded by a very thick investing membrane, which acts as a most efficient protection to the trace of bioplasm that remains. This being protected resists the influence of extreme cold and retains its vitality until external conditions become again favourable, when the trace of living bioplasm soon increases, pushes through spaces or orifices in the thickened Tecibeaaes much of which it even consumes as pabulum, and the rapid growth already referred to is resumed. 95. Death of the mildew.—If such a living thing be placed under certain unfavourable conditions, its vital properties will be destroyed. The transparent living matter in its interior will shrivel up and die, but this will be attended by no obvious alteration in the external membrane. The part which exhibits form (formed matter) remains ; that which is without form (living matter) is alone killed or destroyed. 96. How is the new matter added produced ?—In the thickening of the outer formed matter then, how is the new material produced? Is the thickening oc- casioned by deposit upon the outer surface of the in- vesting membrane, or is the new matter produced by the soft, formless matter in the interior ? To put the question still more simply, is the transparent capsule, the so-called ceél-wall, formed by deposition of matter from the fluid sur rounding it, as in the increase of a GROWTH OF THE LIVING THING. 61 erystal, or is it formed from within? Which is the oldest part of the capsule, its external or internal surface? If the new matter were deposited upon the outside, we should expect to find that the membrane would become thicker and thicker as the growth of the organism advanced, while the central portion would remain unaltered. This, however, is not the case. On the contrary, we find that as growth proceeds, the wall in most cases becomes considerably thinned. It is clear, therefore, that any increase in size cannot be due to deposition from without. The matter de- posited upon the imner surface of the capsule is always softer than its general substance, and the external surface of old capsules is cracked and ragged. This ragged portion is oldest. Im many of the alge (sea-weeds) this external surface serves as a nidus for the development and growth of smaller alga—a fact which clearly shows it has ceased to be active, is undergoing disintegration, and becoming fitted for the pabulum of other things, and no longer capable of resisting the action of external conditions. This, the oldest part of the capsule, is now undergoing decay, and the small alge are living in part upon the products thus produced. The new material is in- variably added upon the inner surface of the capsule, layer within layer. Ofthe several layersthe innermost is the youngest, and the outermost the oldest portion of the structure. From this it follows that the in- animate material for the nourishment of these living things must pass through the outer membrane, and be taken up by the living matter within, which commu- nicates to it the same properties and powers which this living matter itself possesses, and which it has inherited from pre-existing particles. At present we cannot get further than this. I am ignorant of the cause of the changes which occur, but tlie facts as I have stated them are true. 9%. Importance of these changes in bioplasm.— 62 MICROSCOPICAL PREPARATIONS. This rapid increase of bioplasm under favourable conditions is a fact of the greatest interest and im- portance in reference to certain changes occurring in disease of the higher tissues of plants, animals, and man. For we shall find that just as the bioplasm of the fungus may grow and live and give rise to new bioplasm at the expense of the formed material already produced, so the bioplasm of an elementary part of the highest organism may increase and consume its formed material. In this way we shall see that firm and scarcely changing tissue may become the seat of - active change, and ultimately be removed. Thus is the fatty matter of adipose tissue removed, and the hard, compact tissue of bone scooped out to make room for new osseous texture. In this way the abscess and the ulcer commence, and the “ softening ”’ of cartilage and other hard textures is brought about. The pathological process known as “ inflammation ” is due to the increase of bioplasm. In certaim forms of cancer the process is seen in its most active, and to us, most painful form; for as the growth proceeds, not only is the formed material of adjacent textures rapidly consumed, but no sooner has the soft cancer- tissue been produced, than it is consumed in its turn by new cancer-tissue, and this by more, until an enormous mass of soft, evanescent, spongy texture results, which destroys the poor patient by its enormous exac- tions upon his terribly-exhausted system. MIcrROscoPicaAL PREPARATIONS ILLUSTRATING LEcTURE IV. No. of diameters magnified. 12. Bioplasm in act of division, certilage, newt .. Be ils 13. Bioplasm from mucus from the throat 30 Sats Allis) 14. Spores, &c., sugar fungus a6 au 42 Aen 0).0) 15. Growing spores, penicillium .. 700 16. Growing br anches and fr uctification, spor es, peni- cillium fe a6 ce cielo 17. Budding and branching ai sugar fungus oe 215 18. Masses of bioplasm at. the extremity of radicle ‘of growing potato ve ae oe Oc -- 1380 63 LECTURE V. Of Elementary Organs and Tisswes—Of the Functions of Organs and Tissues—Changes during Infe—Of the Elementary Units—Erroneous views on Cell- Formation—Formation of the Unit or Cell—Formed Matter—Things essential to the Cell—Nutrition of an Elementary Part—Of the increase of Cells— Cuticle—Hair, Horn, Nail—Epithelial Textures hardened with Calcareous Matter—Enamel—Den- tine—Dentinal ‘tubes’ — Of Secreting Cells — Different Products formed by the same Bioplasm— Fat - Cell —Starch - Cell— Secondary Deposits— Ciliated Cells—Pigment Cells—Salivary Corpuseles. 98. Elementary organs and tissues.—The bedy of the adult man or animal is made up of many different organs, which perform very different offices. These all derive the elements of their nutrition from the blood, and are all under the control of the nervous system. The nervous system consists of many dif- ferent parts, but these are all connected by inter- communicating cords or nerve fibres. Hach organ is composed of a great number of elementary organs closely resembling one another, and so combined that the work of all is united together. Every elenentary organ is made up of a variety of textures differing from each other in appearance and struc- ture, and in the offices they discharge. 99. Tissues of a limb.—If a transverse section be made, for example, of the fore leg of an animal, we find externally a texture which is well known to all as the skin—a tissue not simple in its structure, but 64 TISSUES OF A LIMB. made up of several parts, each performing an im- portant office or function. Beneath this, proceeding from without inwards another tissue comes into view, very different from the first, called fat, or as it is termed more correctly, adipose tissue. Beneath this, again, 1s a firm, unyielding, ghstening material, spread out like a membrane, admirably adapted for the protection of the more delicate structures beneath, This is composed of a form of white fibrous tissue. which is called Fuscia. Next to this we come to a peculiar tissue, which alternately becomes shortened and lengthened according as it is influenced by nerves. The change is ‘said to depend upon the property of contractility. Ordinarily, the tissue in question is spoken of as flesh, but we call it muscle. In connection with this, we invariably notice certain cords which are the nerves. Their office is to bring the muscular substance into relation with the brain and other parts of the nervous system, and to convey to it from the nerve centre those various impulses by which not only its contraction and relaxation is effected, but by which the exact degree of contraction willed is established. Besides the tissue described, we observe in various parts of the limb certain tubes, which are of two kinds—the one, with thick, tough, and very elastic walls; and the other, with walls less elastic, thinner, and flaccid. Both sets of tubes are in connection with the heart, but the one set (arteries) performs the office of conveying the blood from the heart to the tissues; the other (veins), that of re- turning the blood from the tissues to the heart, §§ 40, 46. Besides these, there are some very delieate tubes which are called lymphatics, which transmit a colourless fluid from the tissues to the venous circulation. Lymphatics cannot be seen without being filled with some coloured substance. Lastly, we notice the bone, a firm, hard, solid tissue, in the interior of which is a cavity containing that peculiar OF THE FUNCTIONS OF ORGANS AND TISSUES. 65 modification of adipose tissue known as medulla or marrow. 100. Of the functions of Organs and Tissues.—The functions or offices discharged by organs and tissues have been divided into two great classes, the animal, and the organic or vegetative functions. The one class is characteristic of the higher animals only, but the other is common to all living things. This divi- sion, however, is not strictly accurate, for, in man and the higher animals, the so-called vegetative func- tions could not be performed, if the so-called organs of animal life did not act properly. The animal and organic functions of the higher animals are mutually dependent, and cannot strictly be regarded as _ be- longing to separate systems. The so-called animal functions comprise, Locomotion, Innervation, and Special Sense. The vegetative functions so widely distributed, comprise Digestion, Absorption, Circula- tion, Respiration, Secretion, Generation, and Develop- ment, andthe development of Heat, Light, and Hlec- tricity. Inthe lowest organisms, some of the most im- portant vegetative functions are performed through the instrumentality of the general surface; while in man and the higher animals a separate organ is set apart for the performance of each function. If I was con- sidering these different functions, I should commence with the functions of organic life in-the order in which I have enumerated them, for this seems the most natural mode of arrangement. First of all, the food is introduced into the organism, and after being altered by certain preliminary processes, is subjected to Digestion, by which it is rendered soluble, and fitted for the next process, that of Absorption. By this the nutritive material is taken up and introduced into the blood, and ultimately becomes converted into blood. Thus we come to the consideration of the function of Circulation; and as we follow the blood F 66 INCESSANT CHANGE IN EVERYTHING LIVING. in its course through the body, our attention will naturally be drawn to the examination of those re- maining processes—viz., Respiration and Secretion, by which great and most important changes are brought about in the condition of the circulating fluid, various substances being separated from it for ulterior uses, or for complete removal from the body. Lastly, comes Generation, the process by which the multiplication of individuals is effected. 161. Incessant change in everything living.— Living organisms, as well as every particle of ving matter. are incessantly undergoing change in every part, but the rate of change varies marvellously in different cases. Some materials, passing through the stages of living or forming matter, formed matter and pro- ducts of disintegration, ina few minutes, while others last for many years as formed structure, and perform an important office during the whole time. New parts are constantly being formed, which grow, arrive at maturity, pass through certain stages of existence, and then, having performed their office, die, are cast away, and succeeded by others. 102. Of the minute elementary parts of an Organ or Tissue.—The changes in question affect every one of the microscopic anatomical elements of which-every tissue and every organ is composed. The anatomical unit, which performs the unit of work, seldom measures more than the one-theusandth of an inch in diameter, and, in some cases, the part possessmg structure and performing function, is far less than this. In order, therefore, to form any correct idea of the changes which go on in every part of the body of a complex living being, it is necessary to study care- fully the structure and the changes of one of these numerous elementary units, of which every tissue and organ may be regarded as a collection. Since the time of Schwann and Schleiden, who wrote in ELEMENTARY PARTS OF AN ORGAN OR TISSUE. 67 1838, every writer on minute anatomy and physiology has described at some length the structure of the “cell.” This “cell” has been regarded as the anatomical unit, and it has been often stated that all the dif- ferent tissues consist of “cells.” The “cell” is a complex body, and different properties have been supposed to be manifested by the several parts of which a perfect cell is composed. In order that certain bodies which could not be included under the ordinary definition of the cell might be comprised in the cell category, the anatomical unit it was sup- posed might be modified in certain special particulars and in exceptional cases. A body in connection with which no cell wall could be detected was supposed to have a cell wall in a fluid state, of the consistence of the soap-bubble: or it was contended that it might have had a cell wall at an earlier period of its hfe; or the cell without wall was called a free nucleus, which it was inferred had escaped from its capsule. Many other ingenious devices have been adopted to evade the difficulty, which has been felt by every one who has examined tissues, of bringing each anatomical unit at all periods of its life into the cell category. But, after all, the simple fact is this, that no “cell” exhibits cell wall, cell contents, and nucleus at every period of its existence, while some cells do not possess any structure to which either of these terms can be properly applied at any period. There are, then, “ cells,’’ consisting of cell wall only, and “cells ”’ consisting of a “nucleus” only, and yet the original definition of cell has been repeated in almost all our text-books even up to this very time. As regards the formation of “ cells,” we have the most contradictory statements. Some tissues are admitted not to be composed of cells at all, by autho- rities who nevertheless cling to the cell theory. So far from the “cell” being the essential and the BE 2 68 ERRONEOUS VIEWS CONCERNING ‘ CELLS.’’ earliest form of every structure, the “cell,” as de- fined, never exists at an early period of development, and although it may be convenient to retain the name “cell,” as representing generally the anatomical unit, we must not in any case expect to find the complex body, which it has been stated over and over again is actually present. 103. Erroneous views concerning ‘“ Celis.-—A!] that can be detected at an early period is a little mass of bioplasm as already stated, § 11,45. In some cases, new centres are to be seen in the substance of this, but the mass may be destitute of these. As regards the so-called cell wall, this is always absent at an early period of development. Moreover, when cell wall or intercellular substance, as it has been wrongly termed, is to be seen, the process of division and subdivision, and all the active phe- nomena, occur in the bioplasm only, and the cell wall and intercellular substance take no part in the process. Dr. Carpenter in this country, Dr. Tyson in America, Dr. A. Nicholson and other observers, have accepted to some extent the views advocated by me since 1860, but the majority of writers continue to teach the old doctrines, taking care, however, to modify certain of the details, and to alter the meaning of many of the terms employed. In many instances, it is to be feared that such attempts serve only to perplex the student more and more. Mr. Huxley continues to teach that, “There is a time when the human body, or rather its rudiment, is of one structure throughout, consisting of a more or less transparent matria, through which are scattered minute rounded par- ticles of a different optical aspect. These particles are called nuclei; and as the matrix or matter in which these nuclei are embedded, readily breaks up into spheroidal masses, one for each nucleus, and these investing masses easily take on the form of ON THE INVESTIGATION OF THE ELEMENTARY PART. 69 vesicles or cells; this primitive structure is called cellular, and each cell is said to be nucleated.” Now it would not be easy to find a paragraph in a work having any pretensions to accuracy which conveyed more incorrect information in the same number of words. Actual observation proves that there is a time when the body has no structure whatever, when there is no matrix, when there are no particles of a different optical aspect, when there are, no nuclei. The matrix never “breaks up” into spheroidal masses, though it may be broken up. The material round the nucleus is not applied to it as an investing mass, for the latter exists before the former, and the nucleus arises in the so-called invest- ing mass. Mr. Huxley has been very severe on text- books, but I doubt if he could point out anything in the way of description more thoroughly at variance with facts than his own description of tissue forma- tion which I have quoted. He is surely laughing at us when he tells us that cell wall and intercellular suvstance become “ variously modified,’ both chemi- cally and structurally, and “ give vise”’ to the pecu- liarities of the different completely formed tissues ! Is this an ingenious device for trying to make the reader fancy that some highly complex phenomenon is being philosophically explained to him by some novel method of circumlocution? The student will how- ever find that the only information he gains concern- ing the formation of tissue is, that cell wall and in- tercellular substance become “ variously modified !” 104. Investigation of the nature of the elementary part.—Ifthe student desires to investigate the changes which occur during the formation of tissue, he will find it desirable to discard entirely all the complex phraseology and arbitrary definitions which have so long retarded, and still retard, progress in this department of knowledge. He will find the phe- nomena far more easy to understand than he would 70 ANATOMICAL UNIT OR ELEMENTARY PART OR CELL. have been led to anticipate after studying the state- ments in elementary treatises. Instead of cells with cell walls, cell contents, and nuclei he will find what IT have already adverted to, simply two kinds of matter—one forming, the other formed. In 1859, I drew attention to the significance of ger- minal matter or bioplasm, and showed that this consti- tuted the organism of the amceba and bodies of this kind, that the white blood corpuscle, the pus corpuscle, and all the so-called naked nuclei, were composed of it, and that it was to be detected in every tissue at every period of life. By changes in the germinal or living matter, the cell wall, intercellular substance, and every kind of tissue, everything peculiar to living beings, results. I described how, im all struc- tures, no matter how they differed from one another, the germinal or living matter could be distinguished with certainty from the formed material, and showed that the iving moving matter in the vegetable cell, the matter of the amceba, and that of the white blood corpuscle, was represented in every cell or elementary part of every tissue of man and animals, in health and also in disease. 105. The anatomical unit or elementary part or ceu.—The living matter, with the formed matter upon its surface, whatever may be the structure, properties, composition, and consistence of the latter, is the anato- mical unit, the elementary part, or cell. This may form the entire organism, in which case, it must be regarded as a complete individual. Millions of such elementary units or cells are combined to form every tissue and organ of each individual man or animal. However much organisms and tissues in their fully formed state may vary as regards the character, properties, and composition of the formed material, all were first in the condition of clear, transparent, structureless, formless living matter. Such matter exists in every growing cell, and every cell capable of growth, contains eS ee eee VARYING PROPORTION OF BIOPLASM IN THE “CELL.” 71 it. The young cell seems to consist almost entirely of this living material—a fact well observed in a specimen of cuticle from the young frog, which may be contrasted with more advanced cuticle from the same animal. In the mature cells of the fully formed cuticle only a small mass of bioplasm (usually termed the nucleus) remains. 106. Varying proportion of bioplasm in the “ Cell.” —In the fully formed fat cell there is so little bioplasm left that it may easily be overlocked. In disease, on the other hand, the bioplasm may increase to three or four times its ordinary amount, when it becomes a very striking object. The ovum at an early period of its development is but a naked mass of bioplasm, with- out a cell wall, but having a new centre and often numerous centres (known as germinal spots or nuclei) embedded in it around these, a capsule or cell wall is ultimately formed. 10%. Formation of the “ Cell.—The mode of for- mation of the cell, or elemental unit, as well as the origin from it of other units, is well illustrated im the formation of the ovum. The cells constituting the tissue of the ovary of the common stickleback are very easily demonstrated, and amongst them are seen true ova at a very early period of development. The youngest of these ova differs but little from the “cells” amongst which it lies. It is, im fact, but one of these which has advanced in development beyond the rest. Small but complete ova may be seen with their bioplasm, or living matter, here called germinal vesicle, surrounded by the yolk which consists of formed matter. In the germinal matter are seen numerous germinal spots, which are new living centres of growth originating in living matter. In these are new centres, and in these last, others would have appeared at a later period. The growth of an elemental unit always takes place from within, so that the surface is always the oldest portion. The 72 OF FORMED MATERIAL AND TISSUE. matter of which the cell wall or capsule is composed was bioplasm long before any cell wall was to be dis- covered. On the formation of a cell of epithelium see § 117. 108. Of formed material and tissue.—The material called tissue, exhibiting a definite structure, is not simply deposited, like a crystal, from a solution of the same substance, as has been suggested by some authorities, nor does it result from the “fibrillation,” “vacuolation,” or ““ stratification” of a previously homogeneous fluid or viscid mass, or by the agegre- gation and coalescence of little particles precipitated from an albuminous fluid, but it is invariably formed from living matter, as this ceases to manifest its vital properties. Every particle of matter that is to be- come tissue must first pass through the living state, and the properties, characters, and composition of the tissue will be determined partly by the internal forces or powers of the living matter acting upon the elements of which it is composed, and partly by the external conditions present at the time when these pass from the living to the formed state. 169. Varying characters of formed matter.— The formed material or matter resulting from the death of bioplasm or living matter under certain conditions varies remarkably. It may be a fluid holding cer- tain peculiar substances in solution, like bile, a viscid matter like mucus, a perfectly transparent structure- less membrane, or a material exhibiting a definite structure. To the latter the term fisswe is usually appled. Tissue may consist of a scarcely visibie web of very delicate fibres, holding in its meshes a perfectly transparent fluid containing but a trace of solid matter. It may exhibit well-defined characters, like cartilage, bone, etec., or it may manifest peculiar and very remarkable properties lke muscle and nerve. 110. Matter essential to the elemental unit or cell. CELLS NOT LIKE BRICKS IN A WALL. 73 —All that is essential in the cell or elementary part is matter that is in the living state, germinal matter, and matter that was in the living state, formed material. With these is usually associated a certain proportion of matter about to become living, the pabu- lum or food. So that we may say that in every living thing we have matter in three different states :— Matter about to become living ; Matter actually living; and Matter that has lived. The last, like the first, is non-living, but, unlike this, it has been in the living state, and has had im- pressed upon it certain characters which it could not have acquired in any other way. By these cha- racters we know that it lived, for we can no more cause matter artificially to exhibit the characters of the dried leaf, the lifeless wood, shell, bone, hair, or other tissue, than we can make living matter itself, in our laboratories. Iii. Cells not like bricks in a wali.—Cells forming a tissue have been compared to bricks in a wall, but the cells are not like bricks, having the same con- stitution in every part, nor are they made first and then embedded in the mortar. Each brick of- the natural wall grows of itself, places itself in position, forms and embeds itself in the mortar of its own making. The whole wall grows in every part, and, while growing, may throw out bastions which grow and adapt themselves perfectly to the altering struc- ture. Hven now it is argued by some that, because things, like fully formed ceils, may be made arti- ficially, the actual cells are formed in the same sort of way—an argument as cogent as would be that of a person who, after a visit to Madame Tussaud’s exhibition, seriously maintained that the textures of our bodies were constructed upon the same principles as the life-like wax figures. 112. Cells contain no molecular machinery.— very 74 NUTRITION OF AN ELEMENTARY PART. one who really studies the elementary parts of tissues and investigates the changes which occur as the bio- plasm passes through various stages of change until the fully developed structure results, will be careful not to accept without due consideration the vague generalisations of those who persist in authoritatively declaring the dogma that the changes occuring in cell growth are merely mechanical and chemical, although they are unable to produce by any means at their disposal a particle of fibrine, a piece of cartilage, or even a fragment of coral. They avoid the diffi- culty as regards the bioplasm by ignoring its exist- ence, and attribute to a “molecular machinery” which the mind cannot conceive, and which cannot be rendered evident to the senses, all those wonderful phenomena which are really due to vital power. 113. Nutrition of an elementary part.—We may now discuss what goes on during the nutrition of a “ cell” when it isin a living state. I need not repeat that the active changes are exclusively confined to the bioplasm, and that the formed material is passive, though it may act like a filter, permitting some things to pass and interfering with the passage of others. Well, then, in nutrition, pabulum becomes bioplasm to compensate for the bioplasm which has been con- verted into formed material. Now, let us consider the order of these changes, and endeavour to express them in the simplest possible manner. Let the bio- plasm which came from pre-existing bioplasm be called a; the non-living pabulum, some of the elements of which are about to be converted into bioplasm shall be b; and the non-living formed material resulting from changes in the bioplasm, c. It is to be remarked that b does not contain ¢ in solution, neither can ¢ be made out of b, unless b first passes through the con- dition a, and a cannot be formed artificially, but must come from pre-existing a. In all cases 0 is transformed by a into a, and a undergoes conversion . e OF THE INCREASE OF CELLS. 7) into c. Can anything be more unlike chemical and physical change? Neither a, nor b, nor ¢ can be made by the chemist; nor if you give him bd can he make a or c out of it; nor can he tell you anything about the “‘molecular condition”? or chemical com- position of a, for the instant he commences his analysis a has ceased to be a, and he is merely dealing with products resulting from the death of a, not with the actual living a itself. No wonder then that chemists and physicists persist in ignoring @. 114. Of the increase of Cells.—Several distinct modes of cell increase or multiplication have been described, but in all cases the process depends upon the bioplasm only. It is this which divides: and it is the only part of the cell which is actively concerned in the process of multiplication. it may divide into two or more equal portions, or give off many buds or offsets, each of which may grow as a separate body as soon as it is detached, The formed material of the cell is perfectly passive in the process of increase and multiplication. Even _the apparently very active contractile tissue ot muscle has no capacity of increase or formation. If soft or diffluent, a portion of the formed material may collect around each of the masses mto which the bioplasm has divided, but it does not grow in or move in and form a partition, as has often been stated, §175. When aseptum or partition exists, it re- sults not from “ growing in,” but it is simply produced by a portion of the bicplasm undergoing conversion intoformed material of which the partition is composed. 115. Cuticle or Epidermis——The most external texture of the body, the cuticle or epidermis, is com- posed entirely of cells or elementary parts, some of which are being constantly removed from the free surface, while new ones grow up from below. In the cavity of the mouth, on the tongue, and lining the fauces, epithelium will be found, which, although 76 EXAMINATION OF ADULT CUTICLE. closely resembling that of cuticle, is softer and much more easily investigated. At an early stage of development it is not possible to distinguish the masses of bioplasm which are to form the cuticle from those which take part in the development of the true skin with its nerves and vessels, glands, hair, and adipose tissue. And at the deep part of the cuticle, even in old age, will in- variably be found numerous naked masses of bioplasm, which exactly resemble those present at a very early period of development, § 45. 116. Examination of Adult Cuticle.—Suppose we examine carefully a portion of adult cuticle. The oldest part of this structure is on the outside, aud the youngest, or that which has been most recently formed, is situated nearest to the blood, whence the elementary parts or cells draw their nutritive supply. If we make a perpendicular section of this structure and place it under the microscope, we shall find that in different parts of it the “cells” present very different characters. The deep portion which is nearest to the vessels consists of small masses of bioplasm, surrounded only by a trace of very soft formed material. These are situated very close to one another. A little above this the masses have a more definite arrangement, and each oval mass of bioplasm, now grown larger, § 117, is surrounded by a thin layer of formed material like an external membrane. Still nearer the surface the elementary particles are seen to be larger, both bioplasm and formed material having increased in quantity. As we approach the free surface, the cells become more or less flattened, and the bioplasm is much reduced in proportion. The formed material is harder and more condensed. Lastly, the oldest elementary parts upon the surface, which are rubbed away in great numbers, and possess no bioplasm whatever, seem to be composed entirely of cuticular substance or formed BIOPLASM IN CUTICLE OF DIFFERENT AGES. rz material. They have ceased to grow, and are no longer capable of growth. They are dead. 117. Bioplasm in Cuticle of different ages.— If equal portions of the most superficial and deepest strata of cuticle be taken, the proportion of bioplasm to the formed material will be found much less in the former than in the latter. At the deep aspect, where the elementary parts are being produced, the bioplasm is abundant. Upon the surface, where only old ones, which are about to be cast off, are found, the bioplasm is reduced to a minimum, or has altogether disappeared. Consider how these particles of cuticular epithelium row. Here isa little mass of bioplasm which grows and then divides into two; each of these subdivides, and soon. Now, each of these little bodies absorbs nutriment from the surrounding fluid. It imcreases in size. The older particles on its surface are altered, and appear to be converted into a hard substance, which is improperly described as a membrane (cell- wall). As it approaches the surface, the hard ma- terial, cuticle, deposited layer within layer, becomes thicker and thicker, until at length the mere trace of bioplasm which remains in the centre, being too far removed from the source of nutritive supply to in- crease, perishes ; and the elementary part, in the form of a flattened scale of dry cuticle, having by this time reached the surface of the body, is cast away, while its place is taken by others which grow up from below. 118. Hair, horn, nail— Hair, horn, and nail are epithelial structures, and if we examine the cells or elementary parts at the bulb, base, or growing portion, we shall invariably find numerous small masses of bioplasm like those situated at the deep aspect of cuticle. It is im this situation that the bioplasm divides and subdivides, and the new cells which are formed push before them those previously developed. In the fully formed hardened cells of these structures the bioplasm has completely disappeared, but in 78 EPITHELIAL TEXTURES HARDENED those near the growing part it can always be readily demonstrated by the aid ef the carmine fluid, § 68. The structure and mode of growth of these tissues are well illustrated in the long, ragged, hair-like process found upon the summits of the filiform papillee in the central part of the dorsum of the human tongue, for the individual cells can be distinguished in almost every part of the hair-like process; and as they are not closely matted together, as in the hair, nail, and horn, their arrangement can be very satis- factorily demonstrated. These hair-like processes can be obtained by slightly scraping the dorsum of the tongue with a knife. The bioplasm can be seen, not only in the young growing cells at the base, but in those that are mature in the lower part of the shaft, and with a little management the constituent cells can be isolated from one another and examined sepa- rately. In many of my specimens the bioplasm is beautifully distinct and well coloured by the carmine fluid, while numerous new centres (nucleoli) can be discerned which are more intensely coloured than the rest of the bioplasm. The formed material is per- fectly destitute of any colour whatever. By examining structures of this kind, the student will be able te form an opinion concerning the great advantages to be derived from practising the staining process. 119. Epithelial textures hardened with calcareous matter.—I will now advert to the remarkable changes which occur during the formation of those very hard tissues which are infiltrated with calcareous salts, and in which the bioplasm plays a conspicuous part. In illustration, I will draw attention to the formation of two of the hardest and most durable textures in the body—the enamel and dentine of the tooth. Although, in their fully developed state, these tissues are remark- able for the large proportion of earthy salts they con- tain, there was a time when each was composed of very soft organic matter only. Although no trace of WITH CALCAREOUS MATTER. 79 bioplasm can be detected in the fully formed dentine or enamel of the adult, at anearly period of develop- ment these tissues were represented by masses of bio- plasm only. - Additional interest attaches to the consideration of the structure and growth of the enamel and dentine on account of the different and conflicting views en- tertained concerning their nature—some holding that enamel corresponds to the epithelial textures we have been considering, while it is maintained that the den- tine is more nearly related to bone and the connective tissues. According to this view, the neutral line between the two represents the position of the base- ment membrane in an ordinary mucous membrane. Huxley, on the other hand, and for reasons which seem to me insufficient and unsatisfactory, holds that both enamel and dentine are dermal tissues, and situated beneath basement membrane. Lastly, the position of the vessels as regards the dentine, the manner or growth of both tissues, and the fact of their origin in a coliection of unquestionable epithelial cells, have forced me to conclude that both enamel and den- tine are more nearly allied to epithelium than to any other tissues of the body, and that both are developed on the surface of basement membrane. The tooth grows in a manner so like a horn anda hair that it is difficult * to believe that is is not closely related to these epider- mic appendages, while there are not wanting instances im which an eminence covered with an epithelial tex- ture seems to take the place of a tooth. Hair and teeth are sometimes abnormally developed, and Mr. Darwin has remarked that the teeth of hairless dogs are defective, and that over-hairy men have abnormal teeth. My own conclusion upon this matter, after examining with great care the tooth at a very early period of development is, that the masses of bioplasm concerned in the formation of the enamel and dentine are embedded in epithelium and are arranged in two 80 FORMATION OF ENAMEL, curved lines, one within the other. The slight inter- val between these lines corresponds to the line of junction of the enamel and dentine in the fully formed tooth. From this neutral line the masses of bioplasm of the two rows move in opposite directions. In the outer one each mass diverges outwards from the neutral line while the different masses of bioplasm of the inner row converge slightly as they move in- wards and form dentine in their -wake. 120. Formation of Enamel.—The formation of the enamel may be very successfully studied in the canine tooth of a young pig. In one of my preparations, ob- tained from an injected specimen, the capillaries of the enamel membrane are seen to be well injected with transparent blue injection, and the enamel cells, the bioplasm of every one having been well stained with carmine, are distinctly shown. Each appears as a columnar or cylindrical body, not unlike a cell of columnar epithelium, with an oval mass of bioplasm nearest to its distal extremity. As the bioplasm moves outwards from the neutral line above referred to, it forms the column of soft material which is to become the enamel rod. After some extent of soft tissue has thus resulted, calcareous matter is depo- sited in that part of the column which was first formed. In my specimen several columns can be discerned in which the change has already com- menced. The highly refracting earthy particles con- trast remarkably with the smooth, faintly granular, organic matrix. The deposition of these earthy salts may be due merely to chemical change consequent upon the formation of free alkali in this the oldest part of the organic matter. While this process is going on, the bioplasm in each little column is stall moving outwards, and forming more organic matter, which, in its turn, becomes calcified. This process continues until the formation of the enamel is com- plete, when the vessels of the membrane waste. A FORMATION OF DENTINE. 81 little uncalcified organic matter usually remains upon the outer surface of the enamel. The markings seen in a transverse section. of enamel receive a simple explanation upon this view of the development of the tissue. The outer uncalcified portion of the rods, when acted upon by acetic acid, swells up ; and the appearance as of a membrane covering the enamel is produced. Some have been led to the conclusion that an actual membrane (basement membrane) or mem- brana preformativa, actually existed in this situation. Consult Mr. Tomes’s “ Dental Surgery,” p. 268. 121. Formation of Dentine.—The dentine of the tooth begins to form before the enamel. But very soon after the formation of enamel has commenced the two opera- tions go on together until a short time before the tooth emerges from the gum. The production of enamel is then completed, while that of dentine continues more slowly as age advances, but the development of this tissue does not cease in some cases before a considerable age is reached. In certain instances— as, for example, in the case of the canines of some of the lower animals and in the incisors of the rodents— the formation of both structures continues through life, so that in the teeth of the adult the development of the enamel and dentine may be studied as well as during the very early period of life in other cases. * The oval masses of bioplasm taking part in the formation of the dentine are larger than those of the enamel, and the formed material produced by them appears as a continuous matrix rather than as dis- tinct and separate columns. Moreover, instead of each mass forming a separate oval body, a thin line of tissue is drawn out as the dentine bioplasm moves inwards. These lines of soft tissue correspond to what are generally termed the dentinal tubes, and may be forcibly withdrawn where the process of calcification is nearly completed. In thin sections the corresponding “tubes” from which the processes G 82 OF DENTINAL “‘ TUBES.” of soft tissue have been withdrawn may be also demon- strated. Calcification takes place by the deposition in the matrix of rounded globular masses of calcareous matter, which increase in size and ultimately coalesce. A narrow portion of the matrix extending outwards from each mass of bioplasm still remains permeable, and the process of calcification proceeds so much more slowly in this portion than in the rest of the matrix that the dentine produced refracts differently, and is harder in texture. 122. Of Bentinal “ Tubes.”—The difference in refrac- tion above referred to and always noticed m thin sections has Jed ebservers to regard this more slowly formed layer of dentine as the “wall” of the sup- posed ‘“‘tube.” But in the recent state this ‘‘ tube” is occupied by unealcified matrix, which can be torn away from the already calcified dentine. The caleifi- cation of the formed material corresponding to the “tube’’ gradually proceeds, so that the space or “tube” occupied by soft matter becomes narrower as the dentine advances in age, and at last in many cases the outermost portion becomes completely calei- tied, in which case there is no “tube” at all. The “dentinal tube” of the dry prepared specimen results from the desiccation of the uncalcified organic matter of the recent structure. The greater “width” of the tube near the pulp, and its gradual reduction in diameter towards the surface of the dentine; the existence of soft solid matter in ‘the “tubes,” as was first demonstrated by Tomes; and the relation of the oval masses of bioplasm on the surface of the pulp to the dentine, are all accounted for in the explanation of the development and formation of the dentine above given. 123. Dentinai “Tubes” not canals for conveying fluid.—Is it reasonable therefore to suppose that the dentinal tubes are really channels for the conveyance of nutrient fluid from the surface of the vascular pulp SECRETING CELLS. 83 to the dentinal tissue, as has been so long taught ? There are no tubes fulfiling a similar office in ivory— a tissue very analogous to the dentine. Surely, if the ivory of the elephant’s tusk can be formed and preserved in a healthy state without nutrient fluids being conveyed by tubes to every part of it, it is extremely probable that the dentine of other mam- malian teeth is in like manner destitute of any such special provision, as has been conjectured, for its free irrigation in every part. These tissues really undergo little change after their formation, and such an ex- tensive system of nutrient channels as has been sup- posed to exist would be perfectly useless. The formation of the soft tissue of dentine and enamel affords an interesting example of the growth movement in opposite directions of masses of bioplasm destined to produce special structure. In each case the bioplasts move towards a vascular tissue which recedes as they advance, and which wastes when the formation of the tissues and their calcification have been completed. 124. Of Secreting Celis.—Contrasting in most important particulars with the epithelial cells of the mouth, already referred to in §$ 33, are the “cells” which are concerned in the formation of secretions, of which the liver cell may be taken as an exampler This elemental unit consists of a spherical mass of bioplasm, often containing new centres of growth (nuclei), surrounded by a considerable extent of soft formed material, giving to the whole an irregularly oval or somewhat angular appearance. Sometimes there are two or even three masses of bioplasm in one “cell,” in which case the mass looks more like a portion of a cylinder than a “cell.” The formed material is undergoing change upon its outer surface, and, although resulting from changes in one kind of bioplasm, becomes gradually resolved into sugar and 6.2 84 FLASK-LIKE SECRETING CELLS. amyloid, fatty matter, the resinous salts of the bile, and colouring matters. 125. Flask-like Secreting Cells.—Another type of secreting cell is that in which the secretion is poured into the interior, and, after accumulation, discharged from a free opening at its extremity, the cell remain- ing for some time a fixture, and continuing to dis- charge its office. In the mouth of the boa these cells attain a very high degree of development, and are of large size. They also exist in great number, and some may be found in every stage of formation; for, although each one may perform its work for a certain period of time, the cells are being continually removed and replaced by new ones which grow up from below. Like all other elementary parts or units, these flask-like cells exist first as spherical or oval masses of bioplasm, which then become altered upon the surface, and the formed material constituting the “cell wall’ is produced. In this cavity products resulting from the change of the bioplasm at its distal extremity accumulate, and the cavity becomes di- lated. The accumulation of contents and enlarge- ment of the space proceed till at last the summit of the cell approaches the surface; an opening is then formed at its free extremity, and the contents are discharged. These cells remain for some time in position, constantly discharging the secretion which is being formed by the bioplasm in their interior. The bioplasm remains near the lower attached extremity of the open-mouthed cylindrical cell, and takes up nutrient matter at its lower surface, while at its upper part, which forms the floor of the cell cavity, the bioplasm is gradually changed into the secretion of the cell. This accumulates in the cavity, and gradually escapes from the open orifice. A large quantity of pabulum may pass into the state of bio- plasm, and a corresponding quantity of the latter FORMATION OF DIFFERENT PRODUCTS BY BIOPLASM. 85 undergo conversion into the formed material or secre- tion of the cell, while the entire apparatus hardly changes in volume or alters in form or weight. 126. Formation of different products by the same Bioplasm.—The above is an interesting example of a mass bioplasm giving rise successively to two different products. It first produces the cell wall, and then gives rise to “products of secretion,” the composi- tion and properties of which are entirely different from it. I will now refer to one or two other cases in which substances differing in composition and properties from the “cell wall”? are formed from the bioplasm within the cell. 123. Fat Cell—The fatty matter of the fat cell is formed by the bioplasm after the vesicle or wall of the cell has been produced on its surface. The changes may be studied in the adipose tissue of the white mouse, frog, or other small animal. In the chameleon and many other animals, instead of one globule of oil being formed, and then increasing gra- dually in size, several minute oil globules result and these accumulate in the cell. Beautiful specimens of fat cells at every stage of development may be obtained from the connective tissue of the frog and newt. ~ 128. Starch Cells.—Closely resembling the process of formation of fat in the fat cell is the deposition of starch in the starch cells of many vegetable tissues— as, for example, the common potato. If the gradual changes which take place as the bioplasm becomes developed into the mature starch-holding cells be studied, the following observations will be confirmed. Little insoluble particles of starch are seen em- bedded in the bioplasm of the very young cells. These particles increase in size by the deposition of more insoluble starchy matter layer after layer upon their surface, as in the formation of a calculus until the starch-grains assume the perfect form. 86 SECONDARY DEPOSITS. 129. Secondary deposits.—In some of the cells of the potato the cell wall is thickened by the deposition of ‘secondary deposits,’ in which case no starch granules are usually produced. This thickening occurs only at certain points, leaving shght intervals, through which currents of fluid continue to flow to and from the bioplasm in the centre of the cavity. The pro- cess may continue until the secondary deposit reaches near to the centre of the cell. The channels for access of nutrient fluid to the bioplasm in the centre remaining open, give to the mature cell the stellate appearance familiar to every one who has examined such “ vege- table cells.” Just as the “secretion” in the peculiar flask-hke epithelial cells in the mouth of reptiles results from changes in the bioplasm already described, soit may be said the peculiar “‘ contents”’ or “secondary deposits” of other cells are “products of secretion,” and that they correspond to “‘tissue”’ in other cases. They are all non-living substances, resulting from change in bioplasm, and they constitute different kinds of “formed material.’’ The numerous pigment granules in the large stellate radiating and freely communi- cating pigment cells of the choroid coat of the eye, and those found in various parts of the frog, afford another example of a peculiar material resulting from change in the bioplasm. The formation of pigment com- mences at a very early period of development, and its abundance seriously interferes with the investigation of the structure and growth of the tissues of these animals, in other respects so well adapted for the purpose. 130. Of Ciliated Cells.—The cilia of ciliated cells, like the outer part of the cell, the so-called cell wall, are composed of formed material; but the move- ments of these hair-like processes are due to changes taking place in the bioplasm er living matter. The vibration of the cilia ceases when the bioplasm dies, OF CILIATED CELLS. 87 and is generally influenced by any alteration in ex- ternal circumstances which exert an effect, favour- able or unfavourable, upon bioplasm. The proportion of bioplasm or living matter in ciliated cells is con- siderable, and its relation to the cilia is such as to favour the view that it is intimately concerned in the movements. Nutrient matter is taken up by the mass of bioplasm upon the side opposite to that nearest to the cilia, and it seems probable that the production of formed material, and a consequent alteration in the tension of the texture of which the cilium is com- posed, accompanies each movement. I think that the rate of vibration enables us to measure the rapidity of nutrition, and that the to-and-fro movement marks the change of pabulum into bioplasm, and the latter into formed material. This change, which in many cases is probably continuous, here gives rise to an in- terrupted movement,. perhaps because the elastic porous tissue of the cilium suddenly expresses from its meshes the fluid which had just previously passed into them from the bioplasm. An objection has been raised to the view I have advanced, on the ground that the part of a cilium of ciliated epithelium which dies first is the base, or that part which is nearest to the living bioplasm, not the apex which is most distant and which is un- doubtedly the-oldest part of the cilium and that which was first formed. This argument which has been advanced by Prof. Rutherford, would have been regarded by me as of great importance if it had been proved that the cilium itself was bioplasm or living matter. But so far from this being the case, it is almost certain that the cilium is composed of lifeless passive formed material, the movements of which are caused by the changes effected by the living bioplasm at its base. Now, it is obvious that an impulse forcible enough to produce even considerable movement of the thin free extremity of a cilium 88 PIGMENT CELLS. might be altogether insufficient to effect the slightest motion in the thicker basal portion connected with the surface of the cell, and in very close relation with the bioplasm. In this way we may explain the fact of movement ceasing first at the base of the cilium without resorting to the hypothesis of gradual death from base to apex in a structure which is pro- bably not alive, and the movements of which are not vital movements, but rather the consequence of vital changes in living matter immediately adjacent to it. Cilia are indeed modifications of formed material,—of tissue or of cell wall. 131. Pigment Celis.—In various parts of the frog, newt, and other batrachia are numerous very large and branched cells containing fluid, in which are sus- pended multitudes of very minute particles of pig- ment formed fromi the bioplasm of the cell which is situated in the central part, and is usually obscured by the quantity of pigment present. As in other cases, currents of fluid set to and from this mass of living forming bioplasm. The radiating tubular pro- longations of the cells communicate with one another, and are sometimes filled with fluid having the pigment granules evenly diffused through it, while sometimes the minute dark granules become aggregated round the bioplasm in the centre of the cell, and the radii are destitute of them. The movement of the visible particles of pigment results from. the movements of the invisible fluid, which at one time fills the cavities and tubular prolongations of the cells, and at another permeates the delicate walls, and becomes diffused into the surrounding textures. When the tissues are saturated with fluid, the radii also contain it, and the pigment spreads into the tubular network, but in the opposite condition the particles become aggregated in the centre of the cell, and the walls of the tubular processes approach one another. The opposite con- ditions of saturation of the tissues with fluid and its PIGMENT CELLS. 89 removal, are determined by the altered states of capillary circulation, which are themselves dependent upon the degree of contraction of the small arteries which carry the blood to them; and this is affected by the changes in nerve centres from which the ‘arterial nerves are derived. In this way, I think, may be explained the concentration and diffusion of the pigment in these remarkable cell spaces and channels, which formed the subject of a highly interesting me- moir by Professor Lister, who, however, inferred that the nerves exerted some direct action upon the diffusion of pigment. In order to make this view appear plausible he was, however, obliged to assume the presence of an “apparatus, probably ganglionic in structure, co- ordinating the action of the pigment cells,’* which neither he nor any one else has been able to discover, and the existence of which is for many reasons most doubtful. The fact is easily explained by the altera- tion in the amount of fluid traversing the tissues at different times. When the circulation is diminished or arrested, the fluid in the cells passes into the tissues, the tubes become nearly emptied, and the walls in apposition. The solid particles become con- centrated in the large central cavity of the cell, which is the last part to lose its fluid; but when the circulation is free, and the tissues are abundantly irrigated, the particles spread into the radiating tubes now filled with fluid. Professor Lister himself remarks that post-mortem secondary diffusion occurs in a piece of web “cut out and placed in a drop of water on a plate of glass.” Instead of accounting for this fact by the changes resulting from the imbibition of water, he invents an explanation which I must venture to say does not appear to be justified by observation or experiment, attributing it to the action of hypothetical nerve cells “disseminated among * “Qn the Cutaneous Pigmentary System of the Frog.” Phil. Trans., 1857. 90 SALIVARY CORPUSCLES. the tissues of the web itself.” But even if we were to assume the existence of such a system of nerve cells and fibres, we should be unable to account for the change unless Mr. Lister or some one else could ex- plain how such an apparatus would cause little par- ticles to move to and fro in fluid contained in the © interior of a cell; but we should have to add hypothesis to hypothesis before we should arrive at a plausible solution of the fact, while, on the other hand, a much simpler explanation is afforded without supposing direct nervous action at all. The currents setting towards the mass of bioplasm in the centre of the cell, and the varying quantity of fluid diffusing through the tissues under varying degrees of vascular — distension, which we know actually do occur, fully account for the phenomenon. These pigment par- ticles which we see actually moving prove to us the existence of currents of fluid through tissues to and from the masses of bioplasm. We may be sure that similar changes occur in other tissues, and that in the perfectly transparent anastomosing stellate cells of the cornea, for example, corresponding alterations are continually occurring during life. 132. Salivary Corpuscies.—Another striking ex- ample of movement resulting from changes in the bioplasm or living matter is seen in the rapid move- ment of little particles in the fluid or semi-fluid material of which the salivary corpuscle is in great part composed. Owing to the constant disturbance of the fluid caused by the currents flowing to and from the actively growing lving matter, the little particles suspended are kept in a state of constant agitation, now forced towards the surface, and then as rapidly whirled towards the centre, perhaps sud- denly stopped and driven again in an opposite direc- tion. These movements are very remarkable. The actively moving particles in the interior of the cor- puscle can be seen with a good quarter of an inch MICROSCOPICAL PREPARATIONS. 91 object glass, but they may be well studied by the aid of a twelfth magnifying 600 diameters. The nature of the particles is still doubtful. They closely resemble in most of their characters the minute spores of fungi. Their motion, however, is not due to the particle itself, but is evidently secondary, resulting from the movement of the fluid in which they are suspended. It is possible these minute particles may be the agents concerned in the very rapid conversion of starch into sugar which the saliva is known to effect. Microscopical PREPARATIONS ILLUSTRATING LecTuRE V. No. of diameters magnified. 19. Bioplasm taking part in the formation of epithelium and skin, with vessels, nerve fibres, and other struc- tures .- se ae 3% a oe eae) 20. Epithelium of tongue and subjacent textures at birth 215 21. Epithelium of tongue, old man aged 74 . Bg 2 Ale 22. Papilla of tongue, vessels injected, covered and un- covered with epithelium, adult 130 23. Epithelium, mouth of kitten one day old, showing bioplasm and formed material .. ae role 24, Epithelium, mouth of chameleon, showing large mass of bioplasm (nucleus) with new centre (nucleolus) 215 25. Hairs from surface of tongue, human subject ae 26. Hairs and hair bulbs from skin of the kitten. Ob- serve the great quantity of the bioplasm at base of the bulb where the new growth takes place B= tO 27. Hair, vessels, nerves, and adipose tissue ; ear mouse.. 215 * 28. Dentine and enamel, human tooth .. = ae 230 29. Bioplasm and prolongation torn from the calcified dentine, with “dentinal tubes” .. _ ee OO 30. Enamel cells, pig at birth ye 6c re 215 31. Bioplasm of periodontal membrane, showing beautiful stellate masses, freely anastomosing re ws alo 32. Liver cells, toad ; in tubes of basement membrane... 215 33. Epithelium from mouth of snake, showing large flask- like cells, from the orifice secretion escapes .. 400 34. Ciliated cells from branchiz ; oyster. . oie ey p2LD 35. Pigment cells, frog ; showing pigment granules .. 130 36. Salivary corpuscles showing moving granules within. 700 92 LECTURE VI. Formation of Tissue—Of Hpithelial and Fibrous Tis- sue—Formation of Spiral Fibres—Oontractile Tissue —Nerve Tissue—Formation of Fibrous Tissue in healing of a Wound—Simple Fibrous Cownective —Increase iv Old Age and in Disease—Mode of in- crease in Muscles and Nerves—No Fibrous Connec- tive in Insects—Skeletons of young Organs in the Adult—Interruption of Normal Changes—Vitreous Humnour— Mucous Tissue of Umbilical Cord—Con- nective Tis%se—White Fibrous Tissue—Repair— Bioplasm of Cornea—Bioplasm of Yellow Hlastie Tissue—Ligament of the Neck of the Giraffe. THE tissues of which the internal organs of animals are composed vary remarkably in structure, compo- sition, and properties. We find various gradations of resistance and density, from a texture of such ex- treme tenuity as to be scarcely demonstrable, to the firm, fibrous, cartilaginous, and osseous tissues, the hardness of which renders their investigation dificult. All tissues are, however, formed from masses of bio- plasm alike in general characters, though differing vastly in power. 133. Formation of Epithelial Tissue and Fibrous Tissue-—By many the formation of structures lke epithelium has been looked upon as a process distinct from that which results in the production of fibres. ~ In classifying the tissues, attempts have been made to show that those textures which were composed of multitudes of ‘cells,’ were of a different nature to those which exhibited a “ fibrous appearance.” More careful investigation has proved that these ideas must FORMATION OF FIBRES. 93 be abandoned, and that the formation of all tissues is characterised by changes of the same kind. Whether soft, smooth, structureless material, or firm, resisting fibrous texture is to be formed, the change is effected by a mass of bioplasm which could not be distin- guished from the bioplasm which produces any other kind of formed material. Not only so, but a given mass of bioplasm may, under certain circumstances, form upon its surface a capsule, and so ultimately produce a cell-form, while, under other circumstances, this same mass may form a distinctly fibrous struc- ture, or a firm matrix, having no definite structure whatever. Moreover the bioplasts which are to form the cuticle of the embryo and those which are to pro- duce the fibrous texture of the skin, lie so very close together that no one could say which would take part in the production of one texture and which of the other. They are not separated by any line of demarcation or membrane, and both sets of bioplasts have the same origin. In the process of healing of a wound near the surface of the body, “lymph” is poured oat in which may be found bioplasts which have descended from white blood corpuscles. Of these, some produce epithelium, others fibrous connective tissue, unless they be too freely nourished, in which case they grow and multiply rapidly, and no kind of tissue whatever results, but pus § 43 is alone formed. 134. Formation of Fibres.—Fibres may be drawn out, as it were, from any mass of bioplasm in one, or in two or more directions. The mass of living matter may then assume an oval, spindle-shaped, or stellate form. Thin structureless expansions may be produced directly by bioplasm, or fibrous-like membranes may be formed. The “ fibres’ may run parallel, or may cross at various angles, giving rise at last to a tissue of such extraordinary complexity that it seems almost hopeless to endeavour to unravel it, and impossible to find out how fibres, running in so many different 94. REMARKABLE SPIRAL FIBRES. directions, were developed. By careful examination, however, at different periods of the development of such a tissue, the observer will, in some cases, be able to form as clear a conception concerning the manner in which the interlacing fibres were deposited, as he may gain of the mode of formation of a complex spider’s web, by careful examination at short intervals during its formation, although he has not witnessed the creature actually at work. So delicate are the fibres in some tissues that they can only be detected by resorting to artificial colouring; and careful in- vestigation leads me to think that in many cases in which a tissue appears perfectly homogeneous and structureless, it is really composed of excessively fine fibres, which cannot be clearly demonstrated by the aid of the methods of investigation at our disposal. 135. Movement of Bioplasm im all tissue-forma= tion.—The peculiar characters and arrangement of some structures can be accounted for by the move- ments of the bioplasm during their formation, and conversely we may learn much concerning the move- ments of bioplasm by a*minute and careful investiga- tion of the arrangements of the elementary tissue which has been formed by it. In the formation of the elastic cartilage of the epiglottis, for example, it seems probable that each mass of bioplasm revolves while it forms delicate fibres, which accumulate, and at length appear to be arranged concentrically round the space in which it lies. The fibres, in this case, seem to be formed somewhat in the manner in which the caterpillar spins its cocoon, except that m the case of the tissue, the process is interrupted, while the last is a continuous operation. The attachment of the bioplasm to some of these fibres may be dis- tinctly seen in the particular texture referred to. 136. Remarkable spiral Fibres.—In connection with the ganglion cells of the sympathetic of the frog, I have described a very remarkable spiral CHANGES IN TISSUE AFTER FORMATION. 95 arrangement of nerve fibres, which can be readily explained by supposing movements of the bioplasm, while I believe in no other manner can the facts be satisfactorily accounted for. So also by the careful study of the arrangement of the twisting of nerve fibres in many tissues, we shall become convinced of the never-ceasing movement of the masses of bioplasm, not only during development, but afterwards, during the adult period of hfe. In this way only can many of the highly intricate structural arrangements, familiar to us in many organs of man and the higher animals, be explained. 137. Changes in Tissue after formation.—Changes, however, take place in many kinds of tissue after the formative act has been completed. In some cases the part which was first produced dries up, and gives rise to irregularities or cracks, which appear as peculiar markings, and may be characteristic of the fully formed structure. Sometimes a tissue, which for a long time may appear homogeneous and clear, gradually acquires a fibrous appearance from the tendency of the old tissue to split, or cleave in certain directions, which will, in fact, be found to correspond to the lines in which new tissue material was de- posited at an early period of formation. 138. Epithelial Tissue —One of the simplest forms of tissue found in man and animals, and perhaps that which is produced most easily and most quickly, is cuticular epithelium, § 115. Possessing elasticity, and considerable extensile property, performing the passive office of protecting more important textures beneath it, upon which it rests, and with which it is often connected, this tissue is readily replaced, if removed, and when injured is quickly and effectually repaired. Epithelial tissues exhibit, however, re- markable differences in property in different situations. One may be dry and firm, hard and resisting, forming a sharp point or cutting edge, as in certain kinds of 96 DIFFERENT KINDS OF EPITHELIAL TISSUE. nail and horn; another may be supple and elastic, like the epidermis, or soft and moist, like the epithe- lial tissue of mucous membranes and internal passages, while some forms of epithelial tissue are semi-finid, or more or less viscid, of the consistence of mucus, B4, : 139. Different kinds of Epithelial Tissue.—The student would scarcely believe that the soft, moist epithelium of a mucous membrane was in any way related to the hard dry tissue of which nail, horn, and hair, § 118, consist, or to the hard calcified texture of shell, dentine, § 120, or enamel, § 121; but if he were to examine these textures at an early pericd of their development he would be convinced of their very close relationship, and would find that the formed material was produced in the same manner in them all. It may be truly said that one thing can scarcely differ more from another than the soft, moist epithe- lium of a papilla of skin or mucous membrane does from the firm cuticular tissue of horn or hair, and yet under modified conditions the former may become so altered as to constitute a tissue which any one would admit was closely allied to the latter structures. The fibre-like cells constituting certain forms of hair, horn, and nail are very different from other forms of epithelial tissue, but, as 1s well known, well-developed horns are occasionally produced on the skin, and the horny material consists but of modified epidermis. The long drawn out cells or fibres of enamel and dentine are probably modified forms of epithelium, the formed organic matter of which has been gra- dually impregnated with calcareous particles, § 119. 140. Difference in function discharged by Epithelial jissues.—Nor do epithelial textures differ from one another less remarkably in structure and physical properties than they do in function. The cell which secretes bile, or urine, or gastric juice, § 124, would — seem to be very far removed from the epithelial cell GLAND FOLLICLES AND DUCTS. 97 of the cuticle or of a mucous membrane, for the former are instrumental in the production of secre- tions possessing very peculiar properties and con- tainmg much water, while the last produces only the dry horny matter which accumulates, or a softer material which, however, by gradual drying, may be converted into the same sort of passive substance. The relationship is however distinctly seen in disease, for there are conditions under which secreting cells may cease to produce their characteristic secretions, and shrivel up and waste, becoming at last so changed that some of them might easily be mistaken for a very simple form of non-secerning cell structure. While in “inflammation” the bioplasm of all these cells being supplied with an undue proportion of nutrient material, gives origin to a common form of bioplasm—“ pus.” 141. Gland follicles and ducts.—A gland follicle itself, with its included epithelium, is, in the first instance, but a diverticulum from the duct; which duct is but an inflection of the general surface. In the formation both of the duct and the gland follicle epithelium is instrumental. Young cells may grow in a direction from the duct, and multiplying in num- ber may produce a little collection like that seen in the gland follicle, or a long series may result, as in the formation of the tubes of which some glands are constituted. Hventually the permanent epithelium of the secreting part of the gland differs so much in form and action and properties from that of the duct, that, had we not watched the evolution of both, we should not have been inclined to believe in their common origin. 142. Formation of epithelium and fibrous tissue by bioplasm.—At an early period of development no structural differences can be discerned between the formed material produced by those masses of bio- plasm on the surface of the body which are to give H 98 FORMATION OF GONTRACTILE TISSUE. rise to “ epithelial cells,” and that formed by those beneath which are to take part in the development of ‘* fibrous tissues,” ‘‘ vessels,’ “nerves,” and “muscles.” But gradually the soft mucus-like formed material first produced, disappears, and tissue, exhibiting pe- culiar structure, and manifesting special properties, is slowly formed by the bioplasm. This constitutes the tissue of the epithelial cell, or the fibrous tissue of the subjacent textures, as the case may be. The pro- cess of epithelium formation on the surface haying commenced, continues as long as life Jasts, and the loss of the old epithelial cells is compensated by the production of new ones beneath. 143. Formation of contractile tissue.—One of the most remarkable examples of peculiar structure familiar to us, and one which cannot be at all satis- factorily explained at present, is striated muscle. But we must not conclude that the transverse markings are essential to contractile tissue, for they are com- pletely absent in the case of involuntary muscular fibre. While, on the other hand, there are certain kinds of fibrous tissue, destitute of contractility, which possess distinct transverse markings. Nor are the strie of muscle seen at an early period of develop- ment. They do not make their appearance until contraction of the tissue has repeatedly occurred ; but the fact of their great regularity and constant uni- formity m the same species of animal precludes the possibility of these markings being due merely to some accidental variation in the refractive power of the muscular tissue. It is certain they depend upon the occurrence of important structural changes while the contractile material is im a very soft plastic state. They may be due to the rate of formation of the contractile substance, and the rapidity of the suc- cessive actions of the nerve current instrumental in exciting contraction. The depth of the contracting portions indicated by the varying distances between a \. re) MRRSTIOS OF NESTE TSsiz ae lnmes Se Gitfierent cues ama be sored, far ir gs Bermcer of pec eee bes be emmsntiered tinai the iamsne af the serve Dire er by ts chemical compost. Sach 2 ew & ow ever sci supported by Ses. For when we com w eee the acs Qoede @ ove of he eve TH winch is wndowbtedy the acive and realy essence! peri, and thet wider & shoe Sse @ ee | Melis the meewe cere, we ind thet Ge See qeeesees ai camefeely sep srocere ani Teast mm some amos. locks weary He oriteery Stes Tssne. Indeed. f we were shown ofiy 2 wery small “eee of am es Cylinder of gp See's eve Gre, eed sme, we sbhornld om te able wok comm w os gush ane from the othe. 2-243. Rerecsier of fee — Oo! oo De seo forms of feme wich & most wiikey) aimed Tc eeeeeself nara Shoe Bacdocr wexiiccsl, under dhe mecrscpe a conser eure af 7 100 FORMATION OF CUTICLE DURING HEALING. or combined with it at the time of its origin from . the bioplasm. The gradual production of these fibres may be studied under the microscope during the coagulation of a drop of liquor sanguinis. 146. Formation of cuticle during the healing of a wound, &e.—A modified form of cuticular tissue may be produced in a manner different from that described in § 116. Where the healing process pro- ceeds over an extensive surface after the removal of a considerable portion of skin, new cuticle is at last formed. The formation of new cuticular texture does not only spread gradually towards the centre of the space from the intact cuticle at the margin of the wound, but new points of cutiele for- mation are seen to originate as little islands even in the central part. This cuticular tissue must be formed by masses of bioplasm, which have descended from white blood corpuscles, many of which are usually found upon the surface of a healing wound, having escaped when very small with the serum of the blood through the thin walls of the capillaries.* It mnst be remembered that the particles of bioplasm concerned are the descendants of white blood corpuscles which have themselves descended from embryonic masses of bioplasm formed at a very early period of develop- ment before many of the tissues were formed, and at a time therefore when the capacity for the production of diverse structures was greater than at a later period. The white blood corpuscles are the only masses of bioplasm of the adult that could inherit the diverse powers of embryonic bioplasm, and this perhaps may be the explanation of the greater degree and variety of formative capacity possessed by these as compared with other living particles. 443. Formation of fibrous tissue in healing of wounds.— When a wound in the substance of a tissue * “Qn the Germinal Matter of the Blood.” Mic. Journal, 1868. SIMPLE FIBROUS CONNECTIVE. 101 is repaired, fibrin is first formed from the minute bio- plasts and white blood corpuscles. The bioplasm em- bedded in the meshes of this newly formed web of tem- porary tissue then grows and multiples, and at length massesare formed from which a firmer and more lasting fibrous tissue results. This is deposited in definite layers, and in a definite direction, while the old tem- porary fibrin having served its purpose is slowly absorbed. The changes referred to have been care- fully studied in the fibrin deposited from the blood in the repair of a wounded artery. The characters of the coagulum first formed, and the changes which take place in it afterwards, have been represented in the plates appended to the memoir referred to, “On the repair of Arteries and Veins after Injury,” by Henry Lee and Lionel S. Beale. Medico Chirurgical Transactions. Vol. L. 148. Simple fibrous connective—This very delicate texture, the simplest of all the tissues, is very widely distributed in man and the higher animals. Indeed there is scarcely a part of the body in which traces of it cannot be discerned. From the circumstance of its existing between the more important structural elements of higher tissues, and connecting them to one another, as well as to other tissues, it has been termed connective tissue. It has been supposed that this texture was designed to give strength and support to more important tissues, but it must be obvious to any one who examines any of the organs in question, that the various structural elements afford the most efficient support to one another, and are not in need of aspecial supporting frame-work of any kind. It is indeed very remarkable that such a view should have been entertained, as it is well known that at the time when the more elaborate tissue elements are softest, and therefore most in need of support, that is at an early period of their development, scarcely a trace of this connective is to be found, while, on the other 102 INCREASE OF FIBROUS CONNECTIVE IN OLD AGE. hand, when the textures have acquired considerable firmness, and possess resisting power of their own, this “supporting” connective tissue exists in very large quantity. 149. Increase of fibrous connective tissue in old age and in disease. —The intervening connective, instead of being of advantage to the special elements of the tissue, actually interferes with their action, and its accumulation corresponds with the deterioration of the organ in which it takes place. Old textures differ from young textures of the same kind in the greater proportion of connective tissue present, and this results trom changes occurring in the normal structure. In many painful examples: of chronic disease of im- portant organs which come under the notice of the physician, the premature decay at a time when all parts of the body ought to be still in an active, vigorous state, is associated with abundance of con- nective, this being, in fact, the débris of the more important texture which has wasted. 150. Mode of increase of fibrous connective in muscles and nerves.—It is easy to understand how the connective tissue results during the development of textures in which the permanent type of structure is not manifested until several temporary textures . have occupied the place of that which is destined at last to remain, These temporary textures gradually disappear, leaving a small quantity of what we call fibrous connective, and this collects, in most stances, at the outer part, because the formation of the new tissue takes place in a direction from within outwards. In studying the development of tissues, which consist of collections or bundles of fibres as, for example, muscular ‘fibres, this point may be demonstrated very conclusively. The new fibres originate in the centre, and great differences in character between the outer- most fibres and those situated further inward, will always be observed. From the first the masses of ~ ae eS ee FORMATION OF FIBROUS CONNECTIVE IN GLANDs. 103 bioplasm, situated most externally, only produce con- nective tissue, and the muscle itself results from the development of those occupying a more central situation. The same fact is noticed in the develop- ment of nerve fibres. The masses of bioplasm, situated at the outer part of the bundle, do not pro- duce true nerve fibres, but from them is formed con- nective tissue only. Up to a certain period the formation of true nerve fibres may have been possible, but a sufficient number of perfect fibres having been developed within, the marginal fibres degenerated and took the low form of fibrous connective. LS. Formation of fibrous connective in gslands.— But the nature of this connective, and the mode of its production, are very conclusively determined by in- vestigating the changes which occur during the de- velopment of a gland of highly complex structure, like the kidney or liver of man and the higher animals. At an early period of development the cells concerned in the formation of the kidney, for instance, multiply and become arranged so as to form a cylindrical mass. By their division and subdivision this increases in length and circumference, at least during a certain period, in every part of its extent. At the deep or external por tion of these cells, ad jacent to the vessels, matter is slowly deposited in an in- soluble form, al thus a thin membranous boundary corresponding to the outer limit of the future tube results, and this becomes extended as the cells grow, while at the same time it is increased in strength by the addition of new matter. Between the lines of masses of bioplasm from which the tubes are de- veloped, and those which take part in the formation of vessels and nerves, are a few masses which are not concerned in the formation of any definite structure, but which perhaps take part in the production of a small quantity of intervening substance. The mem- brane becomes further modified by its relation to the 104 NO FIBROUS CONNECTIVE IN INSECTS. nerves and blood-vessels. These were very close to the cells at the earliest periods of development, and a very close relationship between them must be main- tained throughont life, or the free action of the gland would be impaired. Moreover, as the gland which already actively performs its functions grows, new nerve fibres and new capillaries must be developed around the tubes. The position which a capillary or or an ultimate nerve fibre occupies at an early period will ata later time be the situation where a bundle of nerve fibres, or small arteries and veins roust be placed. The structural changes involved in all these altera- tions are considerable. Old capillaries and nerve fibres must be removed as new ones are developed to take their place, and all the original gland cells will have disappeared probably long before the uriniferous tubes have acquired their fully formed characters. But these structural elements are not completely re- moved. There remaims a small quantity of matter which cannot be taken up by the ordinary processes at work. This is no doubt capable of bemg removed like every texture in the body, but its complete re- moval would probably involve the destruction of the gland, while its almost complete removal permits of the continuous development of the latter, and does not interfere with its continuous action. The con- ditions of existence in the case of man and the higher vertebrata, with a few unimportant excep- tions only, permit the very gradual but not absolutely complete removal and renovation of the tissues first formed. Hence, as we grow older the greater’ is the amount of connective tissue that accumulates. 152. No fibrous connective in insects.—In insects, the state of things is very different, and in their textures there is an almost complete absence of con- nective tissue. The organs and tissues of the larva are entirely removed, while new organs and textures of the imago, or perfect insect, are laid down afresh SKELETONS OF YOUNG ORGANS IN ADULTS. 105 and developed ab initio, mstead of being built up upon those first formed. Such complete change, however, necessitates a state of existence during which action or function remains in complete abeyance. In the pupa or chrysalis pericd of life, functional activity is reduced to a minimum, and nothing is allowed to interfere with the developmental and formative pro- cesses. The new and more perfect being which is evolved does not probably retain a trace of the struc- ture of its earlier and less perfect state. Although the elements of matter in the imago are, of course, those of which the larva was composed, they have been as completely re-arranged as they would have been had they been introduced into the organism of another individual altogether. Not only have the old tissues been utterly destroyed and new ones produced, but in many instances these new ones belong to a totally different type; and were it not that observation has taught us that they have been really evolved at different periods during the life of one and the self-same individual being, we should have concluded not only that they belonged to different species, but in many cases to species far removed from one another. 153. Skeletons of young organs in adults.—In ver- tebrate animals there is not an organ in the adult but retains, not only the form which it assumed at a com- paratively early period, but some of the very same tissue which was active in early life remains in an altered but deteriorated state. Hvery adult organ may be said to contain as it were the imperfect skeletons of organs which were active at an earlier period of life. This material which slowly accumu- lates, clogs, and perhaps even in the most perfect state of things, slightly interferes with the free activity of the organ. If from any interference with the changes this unabsorbed débris accumulates in undue proportion, the action of the organ may be 106 INTERRUPTION OF NORMAL CHANGES. very seriously impaired. It indeed soon grows. old, while all the rest of the body may remain young. Its imperfect action deranges other processes of the body, and these react upon it until further action becomes impossible, and death results. The gradual but continuous and regular decay and renovation of an organ is normal in the vertebrate animal. The changes exhibit wonderful elasticity within certain limits, according to the demand for functional activity of the organ, but these limits, narrow in some, wide in others, cannot be exceeded without derangement and slow deterioration resulting. 154. Interruption of normal changes.—This con- tinuous renovation of an organ and accumulation of the skeleton of its earlier periods of existence may, however, be almost suddenly interrupted. In those changes which lead to the formation of pus the re- moval of every texture is as perfect as during the pupa state of an insect, but the bioplasm constituting the pus corpuscles has no power to give rise to that which will take part in the development of new _ tissues, while that which takes part in the removal of the larval tissues during the pupa state does possess this power. When therefore in vertebrata this complete change occurs the organ is destroyed, but a new one is never developed in its stead. A part of a complex organ may be destroyed and removed, but it cannot be formed anew, so that in man the gradual or sudden destruction of a great part of an organ necessary to life cannot be repaired, although in many cases the patient may adapt himself to the altered state of things and live under the changed conditions. The ‘above considerations afford, I think, an explanation of the formation of the so-called interstitial indefinite connective found in greater or less amount in all organs of all vertebrate animals, and of its increase. as age advances. The more regularly, gradually, and perfectly the changes are effected, the smaller will be VITREOUS HUMOUR. 107 the proportion formed, and the more slowly will it accumulate. When this is the state of things in all the organs of the body, health and longevity result. The opposite entails disease and too early death. 155. Vitreous humour.—This texture is so delicate that no structure can be demonstrated in it, even if examined under high powers. It contains so little solid matter, that 100 parts lose by evaporation up- wards of 99. The tissue, however, probably forms a delicate web, in the meshes of which watery fluid is retained. At an early period of development nume- rous masses of bioplasm may be demonstrated in every part of the mass that is to become the vitreous humour, and from each one may be traced extremely delicate filaments, which may be followed for some distance, but are at last lost sight of from their tenuity. Fibres no doubt exist which are too delicate to be seen. As development advances, the adult vitreous masses of bioplasm become separated from one another by an increasing extent of delicate tissue, and many of them disappear. Some on the surface may, however, be detected even in the adult, and probably are concerned in the formation of new tissue at the circumference, as well as in certain changes occurring in disease, which may result in a complete alteration in the character of the vitreous. 156. The mucous tissue of the umbilical cord (the jelly of Wharton) is one of the simplest forms of fibrous connective tissue, and one well worthy of at- tentive investigation. Like the vitreous, it contains very little solid matter. Its mode of growth is inte- resting, and by studying it carefully, we may obtain very accurate information. concerning one way in which interstitial growth and expansion of a tissue in every direction are provided for. In very young mucous tissue oval masses of bioplasm are seen ar- ranged round small circular spaces. They divide and subdivide, and move in a direction outwards from the 108 VIRCHOW’S JUICE-CONVEYING TUBES. centre of each space. From each a delicate fibre extends, which intertwines with the fibres from adja- cent masses of bioplasm. The bioplasm increases at the circumference of each area, while the previously formed tissue remains in the central part. Thus it happens, when the tissue has grown to a certain ex- tent, more or less circular spaces, occupied by a very delicate fibrous tissue, are seen free from any bioplasm whatever, while the latter exists only at the cireum- ference. These spaces increase in diameter as the tissue advances in development. In this way growth takes place equably in all parts of the tissue. The above appearances in the structure of the tissue may be well seen under a low power in suffi- ciently thin specimens prepared as I have described. When examined under a magnifying power of 700 diameters, each elementary part is observed to con- sist, 1, of the oval mass of bioplasm prolonged in either direction for a short distance, and exhibiting oil-globules in consequence of change having taken place after death; and, 2, of the delicate fibrous tissue externally, which may be torn and frayed out without difficulty. 153. VWVirchow’s juice-conveying tubes.—The ex- tensions of the bioplasm into the fibrous tissue have been mistaken for tubes, and it has been stated by Virchow that these tubes anastomose throughout the tissue, and constitute a system of channels for the conveyance of the nutrient juices. But it need scarcely be remarked, first, that the sup- posed channels do not in all cases anastomose ; secondly, that they contain bioplasm and imperfectly developed formed material, not fluid, as has been sup- posed ; and, thirdly, that nutrition is more perfectly carried on by the tissue itself being permeated every- where by the fluid flowing to and from the bioplasm, than it would be by any system of nutrient tubes like that imagined to exist. CONNECTIVE TISSUE. 109 The juice-conveying channels, described by Vir- chow as so necessary for the distribution of nutrient matter to the tissues, thus receive very different interpretation. It is now more than ten years since the views here given concerning the supposed nutrient juice-conveying channels were advanced, and quite time that the question of fact were examined by other observers. It is manifestly detrimental to the inte- rests of science that erroneous views should be repeated year after year, although they have been distinctly proved to be erroneous. 158. Connective tissue has formed the battle-ground of many a scientific conflict, and the most extreme views have been entertained concerning its nature. By some it has been regarded as one of the most im- portant and necessary of tissues in the organism, and as contributing to the support of higher and more com- plex textures, and concerned in the distribution of nutrient material to them. It has been maintained that some parts of the nervous system consist almost exclusively of connective tissue; and this texture has long been regarded as a most important and ne- cessary constituent of nerve organs. Indeed, some have affirmed this to be the tissue in which nerves end. But, in opposition to these views, a great array of most important facts has been advanced. In some of the lower animals remarkable for their elaborate and delicate textures, which one would think really do require support, no connective tissue is to be found, while in the higher animals and man, scarcely a trace of the texture is to be met with at a very early period of development when the tissues are very soft and delicate, and when, therefore, they are most in need of support; at this time also they require a vast amount of nutrient material distributed to them in the most perfect manner, but notwithstanding their necessities, this tissue, supposed to be necessary for the conveyance of nutrient matter to them, is absent. 110 FORMATION. 159. Formation.— Moreover, the mode of formation of connective tissue is opposed to the above theoretical views. Connective tissue results in many cases during the growth of higher and more important textures. The intervals between nerves, muscles, and other tissues, and between the constituent parts of these tissues respectively, are occupied by connective tissue. When a tissue or organ is to be developed, its germ always originates from bioplasm occupying the centre of a collection of masses of bioplasm. As its develop- ment proceeds, the superficial masses of living matter are pushed further outwards; and, instead of taking part in the formation of the particular tissue or organ in question, their formative power is limited to the production of this indefinite fibrous or connective tissue. 160. Connective tissue formed during the waste and decay of organs.—