ject, for the purpose of explaining the instances of chicken pox, that have been mistaken for the small pox; and also to account for the differences in the histories of this disease, as furnished by European writers; and who have not described it agreeably to the appearances and severity it has exhibited during the late epidemic. The committee agree with the European writers in the opinion, that no danger ever attends the chicken pox; that its pustules form much sooner; are irregular in their shape, more transparent, and seldom contain wellformed pus. They agree also, that by the fifth day they are generally drying or disappearing; and that from this period all the symptoms continue to decline, leaving no marks on the skin, excepting in a few instances, or from accident.

Authors have generally remarked, that this disease arises from a specific poison; but it should also have been added, that this poison must necessarily be ephemeral and extremely mild in comparison with small pox, since it is admitted that danger never attends the former; that its largest pustules disappear without the least injury to the system; while the epidemic small pox is generally followed by a secondary fever as a part of a much more protracted disease, the violence of which is in proportion, it is supposed, to the quantity of matter absorbed, and oftentimes places the life of the patient in the most imminent danger. It may also be noticed, that the vesicles of the chicken pox present large and irregular, or only partial scabs, situated on their apices, and do not leave the discoloration of the skin, which frequently continues a very long time after the small pox; that, at the period of desquamation, there are very perceptible prominences in the skin, very easy to distinguish from the even or indented surface left by the small pox; the pustules of which are converted into scabs, or their contents are discharged on the skin.

Authors have stated, that varicella is preceded by a short slight fever, or by a fever of uncertain duration, and that it is not attended by severe symptoms. Your committee, however, have seen it assuming a degree of violence equal to some of the forms of small pox, producing convulsions and great general derangement of the system. They have remarked also what they find to have been noticed by Pinel, Willan, and

others, that the chicken pox may be confluent to a great degree; and they believe that it may be protracted to a longer period even than small pox, owing to the partial eruption of pustules, and the successive formation of others for many weeks; that the eruption may be more abundant on the face and head, than on the back and breast, and that it may even occasion a swelling of the face.

It has been further represented, that the chicken pox depends upon a specific contagion; that it affects a person but once in his life, has a great resemblance to the small pox, and is communicable by inoculation with the lymph of the vesicles.*

Whether the aggravated form of chicken pox that has been observed during the last autumn and winter was owing to any peculiar atmospheric constitution, or other cause, and whether it is to be considered a special variety of chicken pox, to be added to the form most commonly described, your committee will not venture to decide. They can however affirm from observation and conviction, that numerous instances of the prevailing form of this complaint, being slightly noticed, and occasionally mistaken, have contributed greatly to multiply reports of the failure of vaccination. They have been repeatedly called to witness such instances of the failure of vaccination, and of pretended or imaginary cases of the small pox, which would be erased much sooner from the skin, than erroneous impressions could be removed from the minds of the uninformed and inexperienced.

From the foregoing statement of the origin and progress of the late epidemic, and of the causes of reports unfriendly to the vaccine disease, your committee may be allowed to sug. gest, that more effectual means should be devised to guard against any future occurrence of the small pox; to promote a more general adoption of the practice of kine pock inoculation among the poorer classes of the community, and to introduce such improvements as are best calculated to obviate the evils that may arise from the failure of vaccination hereafter.

* Bateman on cutaneous diseases.

Note. The eruption of varicella is sometimes preceded by a general rash on the skin, similar to what is observed in small pox.

·

On all these important topics, the committee have to offer what they believe to be conclusive and practical remarks: they would premise, however, some observations respecting the "improved mode' of vaccinating lately proposed by the London Vaccine Institution. It appears that the board'* attributes many failures to vaccinating by a single puncture, and afterwards opening the vesicle, and taking a portion of the lymph for the purpose of propagating the infection. Should the doctrine thus officially promulgated by that institution be true, your committee must necessarily infer, and deeply lament, that vast numbers of persons in this and in other countries, remain only delusively protected by vaccination, since the practice thus reprobated has been very generally approved, and has as generally prevailed throughout Europe and America.

The "board of the London Vaccine Institution" have not been at the pains to state the period of the disease at which the puncture or rupture of the vesicle may interfere with its operation on the system; but inasmuch as the effect of the disease generally takes place on the seventh or eighth day, it may be inferred, that the board apprehended that danger may arise from puncturing the vesicle at any time during the existence of lymph in it. With all deference and respect to such high authority, your committee owe it to themselves, to the Medical Society of which they are members, to the laws of the animal economy, to the laws of contagion in general, which they consult, and to the tranquillity of the public mind, which they wish to establish,-explicitly to declare their dissent from the doctrine promulgated by that board, and which is founded upon the principle, that by diminishing the quantity of the vaccine virus, or lymph, after it is formed in the part, the operation of the disease on the system is in danger of being destroyed or enfeebled, notwithstanding the lymph is secreted in the part, and possesses all the characteristics of the vaccine virus. Admitting, for the sake of argument, that it is experimentally proved that a small pox pustule, and a kine pock vesicle, can be locally excited, and can respectively furnish genuine virus, in persons who have already had those

Medical Repository, No. 2, vol. III. N. S. p. 201.

diseases; yet it is believed to be utterly unknown, that a true and genuine pustule of small pox, or vesicle of kine pock, can take place without infecting the system, if susceptible of either of those diseases at the time. No contagious disease, after being communicated by the inoculation of its specific virus, is known to have been arrested: this can only be done by the immediate destruction or removal of the poison, or of the part to which it has been applied, before absorption has taken place. Absorption of the inserted virus is absolutely requisite to excite its specific disease, in a person in whom the susceptibility to it exists, or has not been destroyed; and it must have had a complete evolution in the system, or have exercised its peculiar property in producing an appropriate disease, when the pustule exhibits, among other characteristics, the presence of lymph, or matter capable of reproducing the same.

If the bursting or puncturing of the vaccine vesicle could endanger or subvert the efficient operation of the disease on the system, the genuine character of the vesicle should be completely destroyed, which has not been observed in any of the numerous instances that have occurred; for, whatever injury the vesicle may have sustained, the peculiar scab, more or less expressive of the disease, is reproduced, and its peculiar mark, more or less enlarged, is left on the skin. Your committee are not acquainted with any thing that can possibly interrupt or prevent the constitutional operation of the kine pock in a susceptible subject, excepting a morbid state or action of the system, which may preclude every character of the disease, or a constitutional excitement inimical to cow pock, and giving rise to many of those irregularities "observed in the progress of the affection at the part inoculated."*

It is well known that Mr. Bryce, of Edinburgh, several years ago recommended a process as demonstrating the constitutional operation of the vaccine disease, and which consisted in performing a second vaccination about the end of the fifth, or beginning of the sixth day after the first. If a constitutional affection be produced by the first, the progress of the second vaccination is so much accelerated, that by the eighth or tenth day from the period of the first vaccination, both

Bryce on Cow Pox.

vesicles are equally far advanced, the second vesicle being a miniature likeness of the first. Against the truth of this fact, or the conclusion which it furnishes, no possible objection can be made; it implies that additional vesicles, so far from imparting more power or energy to the virus previously inserted, are altogether under the control of the first. It is of little importance how many vesicles there may be, or at whatever time they may be excited, since one alone fully imparts the constitutional action of the disease. Experience also offers another fact to prove the inutility of additional vesicles to secure or complete the action of the disease on the system. If additional vesicles impart strength or preventive power to the process, how is it that spontaneous vesicles do not occur in the most active cases of that disease? There are various degrees of activity in diseases arising from specific contagions. Thus the vaccine sometimes excites high fever; produces an uncommonly large vesicle, attended with an unusual degree of inflammation, and secondary suppuration; but it hardly ever creates an additional vesicle; at least so very rarely, that the oldest vaccinators have not perhaps witnessed it more than once or twice. Your committee conclude, that the mode recommended by the London Vaccine Establishment, of exciting two vesicles instead of one, is never absolutely necessary; and that the utility of it can only be urged as an additional security to the introduction of the virus, by multiplying the chances of success.

A very extensive and dangerous source of error arises out of the idea of a certain spurious vaccine disease, and a certain spurious vaccine matter. It may be traced to the written and oral opinions of the earliest vaccinators, who did not discriminate between an imperfect and defective operation of the system, and a supposed specific matter, which has since been thought capable of producing a specific spurious disease. Great stress has been laid on this subject, without offering the least direct or convincing proof of the reality or existence of such. an article as a spurious cow pock matter. From whence does it proceed, and where shall we search for it? Does it originate in the cow, and is it thence perpetuated by inoculating the human body, or is it spontaneously generated in man? Is it