feeding, and old age, that I am reluctant to record the results I obtained, as I believe that they cannot be accepted as affording a good example of average rate. The velocity of the current in the right carotid measured only 370 millimeters, that in the metatarsal artery showed a velocity of 78 millimeters, and in the maxillary artery 126 millimeters per second.

Of course my experiments were not confined to the carotid arteries, and I now proceed to state briefly a few of the general results of experiments on the principal vessels. I should mention that dogs were the subjects in all the following

cases.

Axillary Artery.-As the result of twelve experiments on the axillary arteries of dogs, I would state the average velocity in this artery to be about 430 to 440 millimeters per second.

Brachial Artery.-The brachial artery of seventeen dogs was opened, and the average velocity found to range between 400

and 430 millimeters.

Radial and Ulnar Arteries.-These arteries were experimented on in eight cases, and the velocity in each was generally from 360 to 400 millimeters in the second.

Femoral Artery.-The femoral was opened twelve times, and the velocity found to be very nearly equal to that of the axillary.

Popliteal Artery.—The popliteal was operated on in only four cases, and the velocity in each case was 410, 415, 425, and 400 respectively.

Tibial Artery.-This artery, in seven cases, showed an average velocity of 330 millimeters.

Metatarsal.-Five arteries were opened, and showed a velocity of between 210 and 250 millimeters.

On one occasion I attempted to take the velocity of the abdominal aorta, but the experiment was unsuccessful.

From my observations I am enabled to corroborate the statement of Volkmann respecting the jerking character of the arterial currents. I was also led on several occasions to put to the test of experiment Volkmann's assertion that the velocity is lessened by loss of blood. On three occasions dogs were submitted to experiment about an hour after severe depletion. In one case the velocity of the current in the right carotid showed a rate of only about 270 millimeters. In the other case the velocity was about 320, and in the last instance the rate per second was 345 millimeters.

I have instituted several other original observations, with a view to determine the effect of the heart's action on the velocity. I, however, decline to publish the results until I have studied the subject more extensively.

It will be seen, on a reference being made to the writings of Volkmann, that the results obtained with his instrument differ considerably from those afforded by mine. I am indebted to Dr. H. Bence Jones for a very valuable suggestion, whereby I was enabled to test the exact differences afforded by experiments with the two instruments. He proposed that I should insert my hæmodromometer into the artery of one limb, and a Volkmann's instrument into the corresponding artery of the other limb.

Last year I followed this method of experiment:-A dog about two years and a half old was bound to the operating table. The left carotid was first opened, and circulation established through my instrument. The right carotid was then exposed, Volkmann's instrument adapted, and the results noted. Volkmann's instrument showed a velocity of 320 millimeters per second, whereas the velocity according to my instrument reached the rate of 430 millimeters! The instruments were now reversed-Volkmann's instrument being inserted into the left carotid and mine into the right. The velocity, according to Volkmann's apparatus, was 325 millimeters; and, according to mine, it was very nearly 440 in the second. This experiment was quite sufficient to demonstrate the fact, that a much greater velocity would be registered by my instrument than by Volkmann's, and the result of many subsequent trials on the same plan were abundantly confirmatory.

The experiments which I have made on the circulation in the veins have not been nearly so numerous as those performed on the arteries, inasmuch as I was anxious to study the velocity of arterial circulation thoroughly, before turning my serious attention to that of the veins.

The only veins I operated on were the external jugular, the basilic, and the femoral.

In the external jugular on two occasions I found the velocity to average 400 millimeters per second. The femoral was five times operated on, but showed some variation in the velocity; in one case it was 435, in another 420; in two it reached 440, and in another case it only reached in a second 400 millimeters. The basilic showed a velocity in three cases averaging 350 millimeters. I hope to prosecute my researches on the velocity of venous circulation when I have completed my study of the velocity of the current in the arterial vessels.

I shall now briefly recapitulate the general conclusions which I have arrived at from a consideration of the results of my experiments.

I. The average velocity in the carotids of dogs is at the

rate of 400 millimeters, or sixteen English inches, per second.

II. The rate of velocity is always greater in the female than in the male.

III. Velocity suffers a decrease from hunger.

IV. Velocity is greater after a full meal.

V. The effect of hunger on velocity is more apparent in the female than in the male.

VI. Velocity in particular arteries is influenced by posture. VII. Velocity varies with age, but the variation is more marked in the male than in the female.

VIII. Velocity varies with the time of day.

IX. Velocity varies slightly according to size.

X. Velocity is affected by medicinal agents.

XI. Velocity is greater in the larger arteries, and in those nearest the heart.

XII. Velocity is decreased by loss of blood.

In concluding this paper I must again remind my readers, that the experiments herein recorded have merely been selected from a voluminous series of notes, and that the conclusions at which I have arrived have not been based on the few leading facts herein mentioned, but have been justified by the results of some 300 experiments.

When I shall have prosecuted my researches still further under different conditions, on other animals, and with other objects in view, I trust that physiologists will then be qualified, from actual experience of, and experiments with, my instrument, to correct and assign to my researches whatever value may attach to them.

I cannot conclude without expressing my thanks to the many eminent physiologists who have so kindly favoured me with their opinions of my instrument, and with suggestions for its improvement. More than all, my thanks are due to Dr. Macdonnel, of Dublin, for his valuable advice, for his great kindness in offering to place his library at my service, and for many other acts of kindness.

I need not say that it is scarcely likely that a hæmodromometer will ever be used on the human subject; and the question would now arise-how can we ascertain the average velocity of the blood-currents in man? I cannot answer the question, but I do not despair of being able hereafter to establish some law, whereby we may be able to calculate with tolerable certainty the velocity with which the blood circulates in the human subject.

ART. V.

Miscellaneous Contributions to the Theory of Pathology. By JOHN W. OGLE, M.D., F.R.C.P., Physician and Lecturer on Pathology at St. George's Hospital.

(Continued from vol. xli, p. 234.)

CHAPTER II.

Containing the history of a series of Fatal cases of Idiopathic and Traumatic Tetanus, and of cases which may be called Tetanoïd.

The following cases are intended to illustrate the phenomena of tetanus, and the appearances presented on post-mortem dissection. Almost all occurred at St. George's Hospital, but I shall subjoin additional cases which have, from other sources, come under my notice.

I have purposely, with a few exceptions, only quoted those cases of tetanus which proved fatal, and were examined after death.1 One or two of the cases have been cited already in the periodicals, and to the citation of these cases I shall refer.

As I have done in respect of the cases of chorea included in Chapter I., at the conclusion of each case in the present series, I shall notice any particulars which strike me in its history, and at the close sum up the general inferences and observations which the cases collectively suggest.

CASE 1.-Tetanus apparently following cold and exposure.

Richard H—, æt. 37, was admitted into St. George's Hospital May 28, 1841, with symptoms of tetanus, but the course of the disease has not been recorded. It is stated that he had suffered no accident, but that he had led a very irregular life, and of late had been exposed to damp and wet, sleeping in the fields, &c. He had been ill for three days before admission, and died April 5th, about the twelfth day after the accession of the attacks.

On post-mortem examination, excepting rather more than usual vascularity of the cranial membranes, all the various parts of the body appeared to be healthy.

Remarks. The only points of interest in this case are-1st, the absence of any traumatic cause of the disease, according to the

1 Among those which proved fatal and were not examined was an interesting case of traumatic tetanus, under the care of my colleague Mr. Holmes and myself, treated by nicotine, and recorded at length in the Medical Times and Gazette,' 1865, March 12, 1864, p. 277.

history given; 2nd, the time of death being about twelve days after the commencement of the symptoms. [106.]

CASE 2.-Tetanus following sloughing of a wound.

Frederick Bwas brought into St. George's Hospital September 19th, 1841, with a sloughing wound at the inner and middle parts of the foot, and affected by tetanus; but no history of the attacks or of their cause has been given. He died on the 22nd of the same month.

On post-mortem examination, a portion of hard leather was found embedded in the wound of the foot, the parts around being inflamed and sloughy; the inner division of the inner plantar nerve was found to lie directly below the wound of the foot, and to be surrounded by a thin screen of a yellow colour; but the nerve was itself healthy, and so were the nerves of the limb generally. The arachnoïd cavity in the spinal column contained rather more fluid than usual, and the blood vessels at the posterior part of the cord were gorged, but in other respects, excepting some congestion of the lungs, all the parts of the body appeared healthy.

Remarks.-Though details of the history are wanting, yet it is worthy of note that the nerve implicated appeared to be healthy after death, notwithstanding that the wound was in a sloughy state. [156.]

CASE 3.-Tetanus of traumatic origin, Softening of the spinal cord, &c.

Thomas C was admitted into St. George's Hospital April 8th, 1843. No history was recorded excepting that he had symptoms which were very like to those of tetanus. He died on the 18th.

Post-mortem examination.-Bruises of the body and an extensive sloughy wound exposing the os calcis existed. The peroneal nerve was exposed, and seen to be of a canary colour and very firm in the slough. Above and below the injury the nerve was softened and white.

1 During this year, 1841, the following case of convulsive fits of pain, attended by opisthotonos, occurred in our hospital:

Wm. S, æt. 22, was admitted Dec. 1st, 1841. The tongue was clean, the pulse not full or strong, skin cool, bowels regular, urine natural, appetite good. He complained of most acute pain in the right temple and cheek-bone-not in the jaw-bone-in the right ear and round to the back of his head, down the neck and across the loins, not at all in the hands or legs. The pain was not constant, but came on in fits, during which he was obliged to fall and lie with the head and back curved backwards. The pain sometimes lasted an hour, more or less, and recurred once in two or three days severely, but he felt a little of it continally. Had been subject to it about a year and a half. His friends attributed it to a fall on the back of his neck on some stones, but he did not himself do so. He died very suddenly, but was not examined after death.