bered, themselves gross masses, if they, in mass is drawn in through the actual subtheir turn, are compared with the literally stance of the investing film, being filtered immeasurable masslets which are used in through its invisible and almost inappretheir fabrication. Each separate corpus- ciable pores. The imbibed food is approcle is, itself, individually made up of parts, priated, in the first instance, to the enor particles, that can just be discerned un-largement and renewal of the aggregation der the highest powers of the microscope of living molecules within the cell, and performing the peculiar vital movements then to the construction of further addi that have been described; and these parts, tions of formed substance, which are reor particles, are themselves made of yet turned to the outer surface of the living other constituent parts also unquestiona- corpuscle, and are there plastered round bly of complex constitution; that is, of the interior of the cell-wall, thickening material which has had, at least, several and strengthening it, and otherwise chang different kinds of elementary substance ing and modifying its character. All the brought together to accomplish its forma- various textures of the living animal body tion. Indeed, it may be unreservedly stat- -bone, cartilage, membrane, flesh, and ed, as an axiom of physiological science, brain - are. indeed, constructed in this that the ultimate spherules, or molecules, way. Whenever such a proceeding is reof which food-substance is composed, and quisite, a considerable number of the comof which living texture is built, are so very pleted vesicles are fitted and fixed togethsmall that they are removed quite beyond er to fabricate continuous texture, and the the sphere of visibility, even when this is fabricated mass is then permeated by deliextended to its utmost range by the great-cate channels and tubes so contrived as to est powers of the microscope. The material substance in which the special changes are brought about that convert dead matter into living matter cannot be seen by human eyes. They occur in a region of material existence that is altogether beyond the reach of the visual powers which have been accorded to man. They cannot, therefore, be made the object of the direct observation of human philosophers. This, no doubt, is one reason why human intelligence has failed hitherto to unveil this particular mystery, and to demonstrate what life is.

enable them to bring in fresh supplies of the nourishment that is still needed for the. support and perfection of the vesicles. As the development of the building-up vesicle proceeds the living internal germ becomes continually less and less, and so dwindles away, while the outer-formed investment becomes thicker and more pronounced in its structural character, until at length the living germ disappears altogether, and a formed, but no longer living, "cell" remains as the final result of the operation. Cells, or vesicles, are so commonly formed under the constructive energy of corpuscular aggregations of bioplasm, that for a considerable time it was believed the cell was the elementary and basal form of life

the structural condition of formed substance which was indispensable to the reception of vitality, and the wasting enclosed germ, under the specific denomination of nucleus, was held to be, not the residue and remainder of the earlier and more actively vital state, but the "seedgerm" which was to lead up to matured vitality. It is now, however, understood that it is exactly those aggregations of bioplasm which have the least trace of an external investment of formed substance that are endowed with the most energetically vital, and especially reproductive, power; and that it is those which have most effectually shut themselves up in an outer case of their own formation that are, on the other hand, the least energetically vital.

The "for ned substance" made by the agency of living "bioplasm "is necessarily placed, in the first instance, immediately outside of the vital and generating mass; it is thrown off, so to speak, to its outer surface. In the case of small isolated aggregations of living substance, such as are the blood-corpuscles now under consideration, the substance, thus generated and thrown back to the outer surface of the corpuscle, may be scattered at once into the general current of the blood, as most probably happens with the great part of the fibrin that is thus fabricated. But, in other instances, the formed substance is retained around the aggregation of bioplasm and condensed into a kind of investing film. In other words, the little living body encloses itself in an outer coat of its own making; and so becomes what is termed, in physiological language, a "vesicle," or "cell." When the outer case, or cell-wall, of formed substance has once The colourless blood-corpuscle of the been framed in this way, all further supply living animal is essentially the representaof formative food for the interior living tive and typical form of primary bioplastic

aggregation which is employed in the econ- long as they are engaged in the work of omy of animal organization, both for re-energetic and rapid multiplication the production and multiplication of like ag- colourless corpuscles are without any gregations, and for the construction of the trace of external investment of formed various fabrics that are finally made for substance. They are merely corpuscular the building up of the body. A very cas- aggregations of bioplasm, and in no sense ual reconsideration of the especial charac- vesicles, or cells. They only put on the ter of this little typical workman in the la- external investment of formed substance, bours of organization will serve to suggest and assume the true vesicular condition, how marvellously it is fitted for the office when they are passing on from the state it has to fulfil. In the first place, there is of active life into the state of formed texits convenient habit of incessant rolling of ture-when they are ceasing to be conitself in every possible direction and into structing agents, and are getting to be every possible shape, and of instinctively constructed material. The coloured bloodinsinuating itself wherever it is possible corpuscles, on the other hand, are more for material substance to find entrance and of the nature of vesicles from the very lodgment; and then, in the next place, first.. The molecules of coloured liquid, there is its no less remarkable habit of in- of which they chiefly consist, are at all cessantly absorbing spherules of organic times enclosed within a delicate investsubstance into the restless vortices of its ment of formed substance. Most probably own mass, and of there changing them in- the small mass of bioplasm, that sets to to "formed substance," the material base work to construct this investing coat for of organized textures. Comparatively few itself, is but a variety of the young colcolourless corpuscles are seen, at any one ourless corpuscle. Colourless corpuscles, moment, in any part of the great current formed out of living bioplasm, grow, malof the circulation, simply because they are tiply, and pass on into the developed state taken up, and used, in the work of conver- of coloured corpuscles. sion and construction almost as rapidly as they are supplied. If they were the final issues, instead of being the material means of the constructive operation, as it will be presently seen their associates the coloured blood-corpuscles are, they would be as numerous as those little crimson bodies. Wherever the hurrying blood gets into channels that retard its onward flow the colourless corpuscles become immensely more abundant, because then their multiplication is continued while their expenditure is arrested. In the extreme capillary channels of the circulation, where the constructive energies of the colourless corpuscles have to be mainly exerted, the motion of the bloodstream is of necessity slow, because the actual area of this terminal network is of some four or five hundred times larger capacity than the area of the main vessel which furnishes the supply. The current of the blood waxes slower and slower as it passes on into the larger space that is laid out for its conveyance. It will be at once perceived how admirably this retardation of the movement of the blood in the minute channels of the circulation, where it is virtually brought into close contact and connexion with the fabrics that are to be operated upon, favours the proceedings of these subtle little fabricators, the colourless corpuscles. The coloured corpuscles of the blood are, however, of a very different nature to their colourless allies and associates. So

The coloured corpuscle is not only of a somewhat smaller size than its pale companion and ally, it is also of an altogether different form and aspect, and is entirely devoid of capacity of intrinsic vital movement. It is swept along in the general current of the blood-stream, and is sometimes a trifle more distended, and at other times a trifle more pressed in. But it exhibits none of the internal unfixedness and restless change of shape that have been spoken of as the leading characteristic of the colourless corpuscle. It is, indeed, an already fixed and fully-developed vesiclelike body, fashioned for particular work, and on that account left with a lower endowment of vital energy. The general shape of the outer envelope is not spherical, but lenticular, compressed in one direction from side to side. As it is rolled along in the channels of the circulation it presents itself sometimes sideways, and sometimes edgeways, to the eye. The sides are not smoothly and evenly curved, but slightly dimpled in the middle, so that they look as if they consisted of a central darker spot and a surrounding ring of lighter hue. The investing coat is soft, flexible, and elastic, and capable of yielding readily to the impression of external force, although destitute of all power of iudependent movement. The substance contained within is a thick crimson fluid somewhat of the nature of highly plastic fibrin, but most probably of still more

elaborate and finished character, and is strongly impregnated with iron.

energy and power, and they keep the blood in the precise state in which it is required to be for the manifold offices it has to accomplish. They convey from the lungs the aerial influence the oxygen - which enters there in the act of respiration, and bear it to the minute capillary channels of the circulation, where its chemical influence has to be exerted in the evolution of animal warmth, or blood-heat, and in sundry other transforming operations connected with the presence of impulse and effort. The particular powers of muscle, nerve, and brain the most highly endowed parts of the living apparatus are unquestionably stimulated and maintained in their fullest energy and perfection by the instru mentality of the red corpuscles.

The question of the actual character and parentage of the red corpuscle, and of the early relationship and affinities of the two corpuscles the colourless and the coloured is perhaps not yet absolutely settled. There are, for instance, experienced and accomplished physiologists who believe that the red corpuscle is formed in the interior of the colourless corpuscle by the development and maturation of a "nucleus," and that the colourless corpuscle is invested by a cell-film, which is burst when the young red corpuscles are thrown loose into the blood-stream. Yet others maintain that the red corpuscle is a porous mass of dead formed structure, containing in its pores coloured living pulp A considerable portion both of the oxy(oecoid and zooid of Professor Brucke), gen gas acquired in the lungs, and of the and that the living pulp can be caused to carbonic acid gas generated in the capillary move bodily out of the containing pores extremities of the circulation, is at all by certain physical influences. Making all times mingled with the blood in the disendue allowance for the "aberglaube " com- gaged gaseous state. The blood contains plexities of this subtle department of phy- as much as half of its own volume of free siological investigation, there remains, gas. In 100 cubic inches of blood there however, safe ground for the conclusion are 50 cubic inches of gas, of which onethat the colourless blood-corpuscle is a third is oxygen on its way to the structformative body of high vital endowment ural penetralia of the fraine, to perform and activity, and that the red blood-cor- there its office of resolution and reduction puscle is a formed body, fabricated from of complex principles; and two-thirds are aggregations of bioplasm by development carbonic acid gas on its way from these and transformation. Day by day, the no- penetralia, where it has been generated by tion that bioplasm accomplishes most of the resolving power of oxygen, to the pulthe broadest functions of organization, and monary and other outlets, whence it has that it is seen so performing them in the to be discharged at once, not only from case of the colourless corpuscles of the the blood, but also from the body. About blood independently of vesicular construc- one-tenth of the free gas in the blood is tion of any kind, and that vesicular for- nitrogen, an element whose presence is mation is altogether a secondary, inde- less perfectly understood. It is a remarkpendent, and ulterior result, is gaining able fact that the blood holds suspended stronger acceptance among physiologists. in its liquid substance a very much larger The enormous abundance of the coloured proportion of uncombined oxygen than blood-corpuscles-the countless millions pure water can contain. This is mainly of them which are contained in the stream- due to the action of the coloured blooding circulation of a single individual, and corpuscles. The red liquid of these little which are being reproduced generation bodies has the power of holding comparafter generation in unceasing succession, atively large quantities of gaseous oxygen from the period of birth to that of final in a grasp so close that it nearly resembles dissolution at the end of the natural term the strong embrace of chemical affinity, of existence-sufficiently iudicates what important agent these bodies are in the economy and operations of animal life. In all probability they contribute, in some degree, to the actual formation of organized structure. But this is not their chief business and purpose; they clearly have a more direct and special commission of usefulness in the living scheme. The coloured corpuscles act specially as carriers of influence, and as equalizers and regulators Oil, derived from the digestion of the of condition. They rouse and sustain vital fatty ingredients of the food, is always

and yet so light that the chemical integ rity and individuality of the agent are not placed in abeyance or interfered with. Some highly oxydizable principles, which are readily corroded by oxygen in other circumstances, pass unscathed with it through the blood in its progress through the frame, on account of the stronger hold exerted upon it by the ferruginous liquid of the corpuscle.

present in the blood in considerable quantity. There is nearly half an ounce of oil in fifteen pounds of blood. A portion of this oil is mingled with the serous liquid. Other portions are mingled very closely and intimately with the crimson liquid of These communicable diseases, to say the red corpuscle, and, therefore, belong to nothing for the present of other kinds of the corpuscular rather than to the serous morbid derangement, are, certainly, all part. The oil-spherules of the serum are engendered in the blood. They are due used up as fuel in the production and to some injurious change brought about in maintenance of animal heat. The oil of the material, or adjustment, that has been the blood-corpuscles, on the other hand, described. The living blood is the seat is devoted to constructive, and not de- both of the disorder that is set up in the structive, work. It is largely used in the individual system, or frame, and of the erfabrication of nerve and brain, and more ratic influence which then carries a simimoderately in that of some other tex-lar state of disorder to other systems and

and life-plasm, throw any material light upon this important consideration?

tensions of the vessels. As the stagnation imal economy. But in "infectious fevers" in the affected part becomes more decided the same depraved and disordered conand more pronounced, the heart augments dition is set up in individuals who would the force of its stroke in its endeavour to not otherwise have experienced it, by their overcome the abnormal resistance, and having been incidentally placed under the under this increase of injecting force the infecting influence of blood already affectfine walls of the delicate vessels yield, so ed by this kind of contamination. What, that their internal channels become en- then, is the precise mode, and effective larged and dilated. In cases of extreme cause, of the communication of the disormischief they even give way, and the rapid- der from the blood of the affected individly growing aggregations of clotted bio- ual to that of the previously unaffected plasm gather outside and around the proper one? Do the researches of the physiolochannels of the blood-flow as well as with-gist into the nature of blood-constitution, in them. There is then swelling in the affected part, in consequence of the stagnation and unnatural engorgement; and there is pain, in consequence of the way in which the unnatural aggregations and engorgements press upon the nerves. There is also increased heat, or burning (inflammatio), which for a long time was conceived to be actual combustion of the texture of the part under the influence of more rapid oxydation, but which is now known to be something very different. In all derangements of this character there is less, rather than more, oxydation and reduction of the complex principles of the textures of the body. The excessive heat is really due to the over-abundant and too rapid formation of aggregations of plastic bioplasm. When the less elaborated material of blood is converted into life-plasm heat is set free, which was previously operative as latent force in holding together its constituents. The movement of the blood having become either sluggish or stagnant, the abnormally increased supply of heat is not carried away, but remains accumulating in the part and giving rise to the burning" temperature which provides the derangement with a name.

A similar condition of too rapid increase of bioplasm, and too lingering motion of the blood-streams, with a tendency to stagnation in the capillary channels of the circulation, when it occurs everywhere throughout the body, instead of being confined to one particular organ, or narrow spot, constitutes the disorder which is known as "fever." In ordinary fevers the derangement is brought about mainly by mere incidental depravity in the formation of the blood; too much of certain adhesive and plastic principles are thrown into it from the food, and too little of certain effete and contaminating principles are removed from it by the agency of the red blood-corpuscles and of the various organs of elimination, such as the lungs, the liver, and the kidneys, which are properly the scavenger department of the an

In the first place, physiological science does show that, in the vaccine lymph, which reproduces the vaccine form of variolar disease when introduced into previously healthy blood, a myriad of minute aggregations of living matter, obviously of very similar nature to corpuscular aggregations of bioplasm, are rapidly produced, and that the power of the lymph to communicate the disease is almost certainly due to these minute aggregations. If they are removed from the lymph by filtering it, the remaining liquid part is found to have lost entirely its vaccinating power: and, on the other hand, the aggregations left when the lymph is filtered away are potent as vaccinating agents, and continue to be so even when they have been approximately dried, and kept in that state for days and even weeks, provided they are replaced in the substance of warm living blood. These corpuscles of vaccine lymph have now been again and again examined by microscopic object-glasses that magnify them some 5,000 diameters, and with these high powers they look marvellously like white blood-corpuscles and exhibit the same inherent power of vital movement that has been described as belonging to those little bodies. There is, therefore, in this instance, actual demonstration of the production in the blood of visible and tangible disease-germs, capable of reproducing specific diseased action in other blood, and which are, to all appearance, living bodies in the sense in which blood-corpuscles are so.

And again, physiological science has been able amply to demonstrate that when mere simple and incidental inflammatory derangement is produced in a living body, some of the plastic material, which goes ir more favourable and normal conditions to constitute healthy texture, takes to producing little aggregations of life-plasm, which have thenceforth lost all power of performing constructive work in the sys