Journ., vol. xxix., p. 490.-Charles Knowlton, in Boston Med. and Surg. Journal, vol. xxx., p. 92-5.-Samuel Kneeland, on Contagiousness of Yellow Fever, in Amer. Journ. of Med. Sciences, vol., ii., p. 45, N. S.-F. W. Sargent, in ibid., vol. x., p. 287, N. S.-O. W. Holmes, in New-England Quarterly Journal of Medicine and Surgery. April, 1843.-M. M. Wilson, in Amer. Journ. of Med. Sciences, vol. v., p. 244, N. S.-Charles D. Meigs, Translation of Calombat d'Isere, Am. edit., and Introductory Essay to Treatises of Gordon, Hey, Armstrong, and Lee. Philad., 1842, 8vo, p. 338; also, Females and their Diseases: a Series of Letters to his Class. Phil., 1848, 8vo, p. 670.John W. Francis, American edition of Denman's Midwifery. (Dr. F., like Dr. MEIGS, is strongly in favour of copious bleeding in the early stages of this disease.)-Willoughby, on Puerperal Fever, in New-York Med. and Phys. Journ., vol. v.-M. P. Dewees, on Diseases of Females.-R. M. Hurton, Am. edit. of Churchill's Midwifery. Phil., 1848, 8vo.-G. S. Bedford, Translation of Baudelocque on Puerperal Peritonitis, 8vo.-S. Bard, Treatise on Midwifery, &c., 8vo.-For various isolated notices on the subject of Puerperal Fever, see different American medical journals. The monograph of Dr. O. W. Holmes and the Lectures of Dr. W. Harris are the most important contributions to the literature of this disease yet made in this country.] PULSE.--Pulsus,-Zovypòs. Pouls, Fr. Puls,

Germ.

CLASSIF GENERAL PATHOLOGY.-SEMEJ

OLOGY.

in London Med. Repos., vol. xv. 1821.-Chapman, Phila- | delphia Med. Journ., Febr., 1824. (Turpentine with Castor Oil.)-Kinneir, Lond. Med. and Phys. Journ., vol. liv.Ehrhart, Med. Chirurg. Zeit., b. iii., 1826. (After general or local vascular depletions, when required, camphor, calomel, and opium. This was the treatment adopted by the author in 1823, '24, '25, &c., and then noticed in the medical journals of the day.)-M. Hall, Commentaries on the more important Diseases of Females, &c., 8vo. Lond., 1827, p. 151, et seq.; and Cyclop. of Pract. Med., vol. iii., p. 548.P. Dubois, in Dict. de Méd., art. Puerperale.-Schmidtmann, in Horn, Archiv. für Prac. Medicin., b. v., p. 27.Schmidtmüller, in ibid., b. v., p. 222.-Desormeaur, Journ. Complem. des Sc. Med., t. xxxvii., p. 209. Medico-Chirurg. Review, vol. vii., p. 201.-Tonnellé and Legallois, in Archives Génér., &c., b. xix.-R. Gooch, An Account of some of the most important Diseases peculiar to Women, 8vo. Lond., 1831.-A. Danyau, Essai sur la Metrite Gangreneuse. Paris, 1829.-M. Nauche, Des Maladies propres aux Femmes, 8vo. Paris, 1829, p. 465.- Baudelocque, Traité de la Peritonite Puerperale, 8vo. Paris, 1830.Beatty, in Dublin Journ. of Med. Science, vol. xii., p. 296, and vol. xvi., p. 340.-Alexander, in Lancet, No. 327, p. 339, and No. 328, p. 373.-Martin, in ibid. Aug. 6, 1836, p. 649.-Michaelis, in Brit. and For. Med. Review. Oct., 1837, p. 517.-S. Cusack, on Puerperal Fever, in Edin. Med and Surg. Journ., No. 98, vol. xxxi., p. 25. Lond. Med. and Surg. Journ., vol. iii., p. 18.-Nonat, sur la MetroPeritonite Révue Médicale Franc. et Etranq. 1837.-J. Davies, in Lond. Med. Repository, vol. xxii., p. 177.-Legallois, Mém. des Mal. occasionées par la Resorption du Pus. Journ. Hebdom. de Med. 1828.Velpeau, Traité 1. The arterial pulse is produced by the blood Elémentaire de l'Art des Accouchemens, 8vo. Paris, 1829, thrown into the aorta by each contraction of the t. i., p. 167.—Anon., in Lond. Med. Gaz., vol. vi., p. 490 left ventricle. There are three elements which Waller, in Med. and Phys. Journ. July, 1830.-R. Lee, Researches on the Pathology and Treatment of some of the contribute to the production of this phenomemost important Diseases of Women, 8vo. Lond., 1833.- non 1st. The arterial tubes or vessels which Duges et Mme. Boivin, Traité Pratique des Mal. de l'Ute- manifest it to the touch; 2d. The blood, or rus, &c., t. ., p. 216.-Ceely, in Lancet, for 7th of March, 1835.-Cruveilhier, Anatomie Pathologique, livr. iv. and contents of these tubes, which, upon receiving .-Tonnelle, des Fièvres Puerperales Observées à la the impulse from the heart, affect the condiMaternité de Paris. In Archives Génér. de Méd., t. xxii., tion of the arteries; and, 3d. The heart itp. 356.-Duplay, in ibid., t. xxxvii., p. 293.-Bartsch, in Lancet, 16th of April, 1836.-Ingleby, on Epidemic Puer- self, which originates the impulse transmitted peral Fever, in Edin. Med. and Surg. Journ. 1838, vol. through the blood to the vessel, and by the veslix., p. 412.-G. Moore, An Inquiry into the Pathology, sel to the touch. According to the conditions Causes, and Treatment of Puerperal Fever, &c., 8vo. of these three elements or constituents of the Lond., 1836.-Y. Ackerley, in Lond. Med. Gazette. 1838. -Paley, in ibid. for 1839.-R. Ferguson, Essays on the pulse-the arteries, the blood, and the heartmost important Diseases of Women, part 1., Puerp. Fever, and to the various combinations which they 8vo. Lond., 1839.-R. Collins, A Practical Treatise on Midwifery, &c., &c., 8vo. Lond., 1835, on P. F., p. 380. may severally produce, will the pulse vary in -F. Churchill, Observations on the Diseases incident to disease, and even in health, although within a Pregnancy and Child-bed, 8vo. Dublin, 1840, p. 283.-E. much more confined range. These three conRaynaud, des Affections Gangrene uses observées chez les stituents of the pulse require an individual Nouvelles Accouchées, 4to. Paris, 1841.-Storrs, in American Journal of the Medical Sciences. Jan., 1843.-O. w. and particular consideration in estimating the Holmes, Of the Contagiousness of Puerperal Fever, in New-states of the pulse, or, rather, as the causes of England Quarterly Journ. of Med. and Surgery. April, 1843, p. 503. (A very able and sensible Memoir.)-Rokitansky, Handbuch der Speciellen Pathologischen Anatomie, b. u., p. 556–579.-Roche, Nouveaux Elements de Path. Medico-Churgic. Paris, 1844, t. v., p. 438.-F. H. Ramsbotham, The Principles and Practice of Obstetric Medicine-Little mention is made of the pulse by HIPand Surgery, in reference to the process of Parturition, &c., 2d ed., 8vo. Lond., 1844, p. 513, et seq.-J. F. Simon, Animal Chemistry, with reference to the Physiology and Pathology of Man, 2 vols. Translated by G. E. Day, 8vo. Lond., 1845, vol. i., p. 282.-P. U. Schleisner, Barselfeberens og den Purulente Infections Pathologie, &c., 8vo.

Kiobenhavn, 1846.

[AMER. BIBLIOG. AND REFER-Alexander F. Vache, Reports of Cases of Puerperal Fever occurring at the New: York Almshouse, in New-York Journ. of Medicine, vol. iii., p. 97-192.-J. A. Davenport, An Essay on Puerperal Fever, in New-York Journ. of Medicine, vol. iv., p. 313.-Austin Flint, Report of Cases of Epidemic Puerperal Fever occurring at Buffalo, New-York, in New-York Journ. of Med., vol. v., p. 25.-C. S. Magoun, in Boston Med. and Surg. Journ., vol. ii., p. 99, v. 33.-William Harris, Lectures on Puerperal Fevers. Phil., 1845, p. 50, 8vo, and in Boston Med. Journ. vol. ii., p. 238, 245.-J. L. Chandler, in Boston Med, and Surg. Journ., vol. ii., p. 341. (Dr. C. describes a singular epidemic in Rutland county, Vermont, in which all the females confined with their first children over a large section of country were attacked, and all others escaped.)John Ware, Account of some Puerperal Cases in the Boston Almshouse, 1823, '4, in New-England Journ. of Medicine and Surgery, vol. xiv., p. 13.-Norman Lyman, in ibid., vol. xii., p. 337.-Robert Kelsey, in Boston Med. and Surg. Journ., vol. xxii., p. 312.-D. F. Condie, in Quarterly Summary of Transactions of the College of Physicians of Philadelphia for May, June, and July, 1841.-Hall and Dexter, in Amer. Journ, of Med. Sciences, 1843. (Some of the best accounts on record of the identity of puerperal peritonitis and epidemic erysipelas.) Also, in Boston Med. and Surg.

these states, and in connecting these states with functional and organic changes--with the manifestations of vital power and action.

2. I. HISTORICAL NOTICES AS TO THE PULSE.

An

POCRATES; and CELSUS notices it chiefly to record his opinion as to its fallacies. GALEN may be justly viewed as the first who attempted to investigate the pathological relations of the pulse, and he did this at great length. abridgment of his treatises on this subject has been made and published by ANDREA LACUNA. As far back, probably, as the days of GALEN, if not even farther, the Chinese had published treatises on the pulse; and by means of their acquaintance with it, and by it chiefly, they pretended to a knowledge of all diseases. The importance attached to the pulse by GALEN, and by all the writers on medicine in Eastern countries, in ancient times, appears to have been such as to have given rise to the greatest charlatanry and pretence in the practice of medicine. It was supposed in those times, and down to the present day in these countries, that the pulse furnished all the information which the physician required, both as to the seat and as to the nature of a disease; and it was not until past the middle of the seventeenth century that attempts were made by BELLINI to

states of vital tone, or different states of vitality manifested by the arterial system, through the medium or influence of the organic or ganglial nervous system supplying it, and are easily made apparent by means of various agents; as, by plunging the hand in warm water, a certain increase of the vital expansion of the arterial vessels will follow, and the vessel will become full and broad; and by plunging the

investigate the subject with some reference to scientific principles; the researches and discoveries of HARVEY having opened paths by which the ruins of ancient opinion might be removed, and laid foundations for permanent structures. The publication of Sir J. FLOYER's "pulse watch," in 1707, first imparted precision to our estimation of the pulse; and various conditions of it, possessing much importance in practice, especially as being sources of prog-hand in cold water, the artery will become nosis, were pointed out by SOLANO in 1731, and more clearly illustrated by NIHELL in 1745, in his "New and extraordinary Observations concerning the Prediction of Crisis by the Pulse." The subject was farther pursued by FOUQUET and BORDEU about the middle of the last centu-in cold water; while the pulmonary artery did ry in France, and towards the close of that century by HEBERDEN and FALCONER in this country; these latter divesting the subject of much of the inanities and puerilities which had become connected with it since the days of GALEN. Although these writers had thrown aside much of the encumbrances under which sound observation was more or less concealed, still correct views as to the states of the pulse were very far from being entertained. Nor could such views be exhibited while the morbid conditions-functional and organic-of the heart itself, the prime factor of the pulse, remained hardly or very imperfectly known.

small and more constricted. In an excellent lecture by Dr. C. J. B. WILLIAMS (Lond. Med. Gazette, vol. xxi., p. 594), he observes, that he repeatedly observed the aorta of an ass recently killed contract very remarkably when plunged not contract so much. The vital conditions of the arterial system vary remarkably: 1st. With the states of vital energy of the whole framewith the states of constitutional power; 2d. With the influence of agents acting externally or internally on the vessels, the operation of agents varying according as they are thus external or internal; 3d. With the conditions of the capillary and venous circulations, and with the freedom from obstacle to the onward transmission of blood circulating through the arteries.

5. (a) When constitutional or vital power is unimpaired, the arterial pulse then presents a state of healthy or natural tone, modified somewhat with the peculiarity of constitution or the amount of vital energy. In these cases the pulse evinces neither broadness, nor expansion, nor softness, nor weakness, on the one hand, nor undue constriction, hardness, or smallness on the other. It is then possessed only of moderate firmness and fulness, its frequency or number in a given period depending upon the action of the heart. When vital power is reduced, and in

3. II. PHYSIOLOGICAL PATHOLOGY OF THE PULSE. Before the various states of the pulse can be duly considered, some notice must be taken of the conditions of each of the three constituents of the arterial pulse-of the arteries, of the blood, and of the heart.-A. The ARTERIES, as I have shown in other places (see articles IRRITABILITY and SYMPATHY), are not inert tubes, but living vessels endowed with certain vital as well as physical properties.-a. Their physical properties are chiefly expansibility, ex-proportion to the reduction, is the tone of the tensibility, and elasticity: expansibility in the expansion of their diameters or enlargement of their calibres; extensibility in their elongation to a certain extent during muscular movements, and other causes; and elasticity, or the recovery of their natural states immediately upon the removal of the expanding and elongating causes. These properties are possessed by arteries in a very eminent degree, and in virtue of their conformation-of their fibrous coats, and of their serous and dense cellular and connecting tunics. They are evinced to a great extent af-nately affect the heart-both the arteries and ter death; but they exist to a greater extent during life, vitality not only endowing these vessels with peculiar properties, but also increasing their physical qualities.

4. b. The vital properties of arteries, and which contribute very remarkably to form the character of the pulse, depend especially upon the organic or ganglial nerves, which not only accompany all the arterial trunks and ramifications, but form reticula around them, and are lost in their fibrous and serous coats; the states of organic nervous energy affecting the vital conditions of these vessels. These conditions or properties are referable to different states of one vital endowment, viz., tone or tonicity. According to the state of vital tone will the arteries manifest a greater or less degree of expansion or of constriction, both when subjected to the sense of sight and when examined by the sense of touch. The expansion and the constriction are

artery weaker and rendered soft, compressible, and otherwise changed according to the states of the blood and heart's action (see § 6, et seq.). When, on the other hand, the vital energy is excited, the state of the vessel is then firm, round, or hard, and otherwise altered with the action of the heart, and the quantity and quality of the blood. Marked modifications in the state of the arteries result from agents influencing the conditions of the organic nervous system; but these agents frequently also co-ordi

the heart; whether these agents affect this part of the nervous system primarily and externally to the arteries and heart, or secondarily and internally to the vascular system, by imbibition and absorption, or through the medium of the blood; the state of the arterial vessels being, in either case, thereby more or less changed, according to the nature of, and the influence exerted by, these agents. The natural conformation of the arterial system is sometimes different in different individuals, some persons possessing a more powerfully constituted state of this system than others, especially in respect of the fibrous coat, the vessels thereby acquiring increased tone, and often a greater degree of hardness or firmness, both in health and in states of excited action.

6. B. The BLOOD is another necessary constituent of the pulse; the uninterrupted column of blood, extending from the commencement

of the aorta to the part of the artery to which
the finger is applied when feeling the pulse, be-
ing essential to the sensation communicated
by the artery to the organ of touch.
It is pre-
sumed, in our examinations of the pulse, that
the states of this column of blood are the same
throughout the arterial system, the difference
being only as respects the diameter and length
of the column, according to the artery which
is felt. This, however, is not always the case,
as slight modifications will occasionally follow
from local determinations, influenced by the
state of nervous power, and from local impedi-
ments or obstructions to the venous or capilla-
ry circulation of a part. But without reference
to these modifications, we shall find sufficient
sources of alterations of the pulse in the condi-
tions of the blood circulating through the arterial
system. The conditions of the blood which af-
fect the pulse are, 1st. Quantity; 2d. Quality,
or alterations in its physical and sensible condi-
tions, and probably also in its vital states.

less tense or oppressed, and more natural, while
it diminishes the acceleration in the former cir-
cumstances, and increases it in the latter.
8. (b) Deficiency of blood is attended by a very
different state of the arterial pulse; the fre-
quency of it depending, as in all other cases,
upon the cardiac action, and the tone of the
vessel very much upon the state of vital power.
When the blood is very deficient in quantity,
the state of the pulse will depend much upon
the power of the vessel, and of the vascular
system generally, to accommodate themselves
to that deficiency. If the vital or the organic
nervous power is not depressed to a very low
state, the vessels will evince merely less ful-
ness, or become more constricted or smaller,
yet, at the same time, soft or compressible.
If vital power is excited or irritated, notwith-
standing the loss of blood, the vessel imparts,
with great frequency, much quickness, or sud-
denness of impulse against the finger, and great-
er constriction. If it be extremely depressed,
the pulse may be either rapid or slow, accord-
ing to the irritability of the heart, but the ves-
sel feels very soft or compressible, the slightest
pressure obstructing its canal, while the impulse
communicated to the column of blood in the ar-
tery is quick or rapid when the heart's action
is excited, the vessel feeling as if it were nearly
empty between each impulse, and is slow, un-
dulating, and weak when the contractions of
the left ventricle are much weakened, and ir-
ritability exhausted. Much, however, of the
changes in the states of the pulse, with altera-
tions in the quantity of blood in the body, is ow-
ing not only to the associated state of cardiac
action, but also to the quality; to the constitu-
tion and states of the blood, physically, sensibly,
and vitally.

7. a. Adverting first to quantity, it is obvious that any deviation from that quantity which is adapted to the capacity of the vascular system generally will affect, in a very sensible manner, the arterial pulse, as respects both the states of the arteries and the contractions of the heart. When there is a due correspondence between the capacity of the vascular system and the quantity of blood circulating in this system, the coats of the arteries will be kept in that state of healthy tension, or tone, favourable to a regular, firm, free, natural, or healthy pulse, varying chiefly in frequency with the state of the heart's action, which will depend upon either exciting or depressing causes.-(a) When the quantity of blood in the system is excessive, more or less of oppression may be evinced in the state of the artery, as well as either of in- 9. b. The quality of the blood, as well as the creased or of diminished frequency, much of quantity, has been shown in various parts of these changes arising from existing states of this work (see art. BLOOD, DISEASE, FEVER, PESvital excitement or depression. Excessive ful- TILENCE, &c.) to be remarkably changed in its ness of blood, however, may exist, and, being sensible appearances, and in its vital states. I attended by congestion of one of the minor cir- have in several places attempted to show that culations of the lungs, of the liver, or of the the blood, in addition either to excess or defisinuses of the cerebro-spinal axis-may not ciency in its quantity, may have either an exmaterially affect the pulse. But as this state cess or deficiency of its red globules, or of its will not long continue without evincing its con- fibrin, or of any other of its constituents; and nexion with either depression or reaction of vi- that it may, moreover, abound in morbid or in tal power, so will the pulse, through the medi- foreign matters, owing either to imbibition and um of the heart's action, be slow or frequent, absorption, or to imperfect depuration and exas well as oppressed; the degree of frequency cretion. Still there are manifestly additional depending on the heart's contractions, and these morbid states of this fluid which also affect the contractions depending upon the state of the pulse, although these cannot be accurately estiorganic nervous or vital influence, and other mated in grade or kind: these are the vital concauses, to be noticed hereafter. The sensa-ditions of the blood, derived from the vessels tion produced by an artery in cases of exces- and body generally, through which this fluid cirsive vascular fulness I have designated that of culates. That there is a very intimate relaoppression, the vessel feeling as if it were kept tion and even connexion between the vital conin a state of tension, or of distention, in the in-ditions of the vascular system and the constitervals between the beats; and, if the pulse be at the same time much accelerated, an idea suggests itself that the heart is excited by the load, and, by its more frequent contractions, is endeavouring to disembarrass itself and the vascular system generally; while if, with this state of the artery, the pulse is slow, the notion presents itself that the organic nervous energy actuating the heart is insufficient for the amount of blood circulating through the frame. Under these circumstances, it is found that the abstraction of blood renders the pulse more free,

tution of the blood, especially of its globules and liquor sanguinis, cannot be doubted; and although the vital states of the blood are derived from or dependant upon those of the vascular system, still they react upon this system, especially if they continue for any time, or are not removed by the efforts of the constitution, or by the aids of medicine.

10. During the progress or continuance of changes in the sensible qualities and vital states of the blood, especially as evinced in the course of rheumatic, inflammatory, or of adynamic,

the qualities of quickness, sharpness, or suddenness of the impulse of the column of blood against the parietes of the vessel where it is pressed upon by the finger, or with the opposite qualities of languor, weakness, smallness, &c., according to the excited, or weakened, or near

12. C. The HEART furnishes, besides frequency, several other qualities, as already noticed, to the pulse. The influence of the heart on the pulse is, 1st. Functional, or dependant upon the strength or weakness of the contractions of the organ, and upon the grades of irritability possessed by it; and, 2d. Structural, or owing to lesions in the parietes of the cavities, or in the

malignant, and pestilential maladies, the pulse can only imperfectly manifest such changes, which usually commence in the nervous and vascular systems, although most apparent in the blood. In cases of vascular excitement, in inflammations, in acute rheumatism, &c., the fibrin of the blood is abundant, and the vitally exhausted irritability of this organ. crasis of the coagulum is firm or even increased, and these states may continue after repeated blood-lettings, showing that these changes of the blood proceed from vascular excitement or reaction rather than that the changes in the blood cause the vascular reaction; the condition of the blood being the effect, not the cause of the state of the pulse, which is always more or less quick, sharp, and rapid, owing to the in-valves or orifices of the heart.-a. The func creased irritability and irritation of the heart. When, with this state of vascular excitement, there is also vascular fulness, then the pulse will feel full and hard, as well as sharp, quick, or rapid; but if the vascular excitement continues, or is fed by irritation or pain, or by the state of organic nervous sensibility and energy, after the vascular system is depleted, or after large losses of blood, then the pulse will become sharp, constricted, rapid, and of various grades of tone or strength, according to the nature and seat of the disease, as observed in acute rheumatism, &c.

11. In cases of depressed vital power, or when the organic nervous energy and vascular action are more or less weakened, as well as otherwise altered, as in the course of malignant, pestilential, or specific maladies, the fibrin of the blood is diminished, the constitution of the hæmato-globuline is altered, and the crasis of the blood remarkably impaired. In these circumstances the pulse is affected, and the experienced and close observer may even predicate from the state of the pulse the character of the changes proceeding in the blood, although he may not infer their exact amount; but according to their nature and extent-in proportion to the loss of vital power and of the crasis of the blood-will the pulse become open, broad, soft, weak, and compressible, the artery suggesting to the mind of the examiner ideas of defective or lost tone, of impaired elasticity, and of relaxation. But with these changes in the vessel others are associated, depending upon the amount of blood and the state of the heart's action. If the blood be abundant in quantity, in proportion to that abundance will the pulse be full as well as broad and soft. The artery will furnish a sensation of largeness, and feel full and broad, but still soft between each impulse communicated by the contraction of the ventricle, the parietes of the vessel feeling as if they yielded to the impulse, especially if the heart's action be excited. If, on the other hand, the amount of blood be deficient, the pulse is not only soft, weak, relaxed, or open, and very compressible, but the vessel feels to the examiner as if it were nearly empty between each wave of fluid undulating through it, the impulse of each wave being quick or sudden while the heart's action continues excited, but weak, or languid, or slow as the irritability of the heart becomes exhausted. The action of the heart will be noticed hereafter; but it may now be stated that, in these as well as in many other circumstances, to it belong those changes in the number of the pulse in a given time with

tional influence of the heart on the pulse varies with different diseases, as these diseases are characterized by excited or increased organic nervous energy and vital power, and increased irritability of muscular and contractile parts on the one hand, or by impaired or exhausted power and irritability on the other. The heart being, by nervous supply from the ganglial and cerebro-spinal nervous systems, and by muscular structure and vascular connexions, intimately associated with all the vital functions, is not only influenced by these functions, but also influences them. But whatever may be the state of the heart's action, thus influenced and influencing, the frequency and the character of the impulse communicated to the column of blood in the artery is produced by the contractions of the left ventricle. When the actions of the heart are unimpaired in tone or in strength, if the irritability of its structure is unexhausted, the frequency of the pulse is seldom very great, although the excitement may be very considerable. In strongly constituted persons the pulse seldom rises above 100 in a minute, even during inflammations; and it is only as the excitement or irritation becomes associated with diminution of vital power-this latter always gradually supervening upon, and increasing with the continuance of excitement or irritation-that the pulse becomes very frequent, or much above 100. In delicate, susceptible, or nervous females especially, the pulse is often very rapid during nervous excitement; or in various febrile or inflammatory diseases, or in states of irritation; but in them power is deficient, and although the irritability of the heart is readily excited, it is the more rapidly exhausted.

13. But frequency of pulse may be occasioned not only by nervous excitement, by increased irritability, or by febrile or inflammatory action, but also by losses of blood, and by the want of due correspondence between the quantity of blood and the capacity of the vascular system in general. It is difficult, however, to determine whether or not the increased frequency be caused by this want of correspondence, and the efforts made to compensate for deficient quantity by accelerated motion, or by augmented excitability consequent upon the loss of blood. Most probably this latter effect is that which is immediately caused by this loss; the former effect, or the compensating influence of accelerated motion, being the result of exalted excitability. But the acceleration of the heart's contractions caused by losses of blood has always a more or less obvious relation to the