Several experimental investigations have been prosecuted to demonstrate the correctness of this view, but with re sults sufficiently variable to leave the subject still not settled or free from doubt. Without attempting to decide the question as to the origin or essential cause of the cow-pox disease, we may assume with great positiveness that the lymph or virus from the cow-pox vesicle,. if properly used, affords a reliable pro tection from attacks of variola in all its forms. The questions of great practical importance then arc: 1. What is the best method of propagating and preserving.
the cow-pox virus in a pure and active condition ready for use? 2. At what age should vaccination be first practiced, and how often should it be repeated to secure reliable immunity from an attack of variola.
In answering the first question it must be admitted that the best method of propagating the virus is from heifer to heifer, in well-arranged establishments conducted with strict regard to sanitary and aseptic precautions, and on heifers in good health. The best time to secure the virus is on the eighth clay after vac cination, just before it begins to look turbid in the vesicle. If it is received into sterilized capillary glass tubes and hermetically sealed it will preserve its activity an indefinite period of time and may be transmitted to any country or climate. But for early use it has been found most convenient to receive it dried on ivory points sufficiently sharp to use for incising the cuticle. By dipping the point in clean water and making the in cisions to the cutis vera and rubbing the abraded surface with that part of the point covered with the virus and then let it remain uncovered until dry, enough is generally introduced to insure the ap pearance of the vaccine-sore at the end of four days. It is thought by many that the making of two or three vaccine sores afforded more perfect immunity than only one.
In order to perform an aseptic vaccina tion, the child's arm is first sterilized for some distance around the vaccine-site, and, after introducing the lymph, the skin is covered over and around the parts, with hot boric gelatin, which rapidly sets into a transparent film, through which the progress of the vesicles can be ob served. On the eighth day the film is quite easily peeled off; the vesicles are then dusted over with boric-acid powder, after which another and thicker layer of the gelatin is applied, and, while setting, daubed with cotton-wool. Occasionally the contents of the vesicles ooze through the film of gelatin, necessitating a second dusting of boric powder. Sinclair (Brit. Med. Jour., Jan. 1, '9S).
Vaccination may be rubbed of its ter rors by the application of liquor potassaa to remove the superficial epidermis. Two or three minutes after the application is made the superficial epidermis may be wiped off with a bit of wet cotton, when a moist shining surface will remain with out bleeding. The vaccine-material is
now applied and allowed to dry in the usual manner. Hutchins (Jour. Amer. Med. Assoc., Apr. 23, 'OS).
A point on the breast two finger breadths outside the nipple and two finger-breadths below it recommended for vaccination. It is not subject to much rubbing from the clothing, and inflamma tion is not likely to occur. Maths (Dent. med. Woch., Feb. 15, 1900).
The most recent mode of the virus for use which is meeting with favor is called glycerinated lymph put up in sterilized glass tubes, convenient to use instead of the ivory points. Concerning the second question it may be said, with much confidence, that the most appropriate and effectual times for practicing vaccination are, first, in, infancy between the age of six and' eighteen months; again when old' enough to enter school,—i.e., at the age of seven or eight years; and a third time at the full maturity of growth,—i.e., tween twenty-one and twenty-five years of age. If every child were effectually vaccinated with pure vaccine-virus ing infancy, again at the commencement of school-age, and a third time in early adult life, in a few years the whole popu lation would be rendered immune and a small-pox epidemic could not occur.
Germany stands alone in fulfilling in great measure the demands of hygiene, having, in consequence of the calamitous small-pox epidemic of 1S70-71, enacted the law of 1874, which "makes vaccina tion obligatory in the first year of life and revaccination also obligatory at the tenth year." The result is that, with a population of 50,000,000, having in 1871 lost 143,000 lives by small-pox she found by her law of 1S74 the mortality dimin ished so rapidly that to-day the disease numbers only 116 victims a year. These cases, moreover, occur almost exclusively in towns on her frontier. If it were true that a good vaccination does not protect from small-pox, we ought to find in small-pox epidemics that the disease dif fuses itself in the well-vaccinated no less than in the non-vaccinated countries. But it is not so. In 1870-71, during the Franco-German war, the two peoples in terpenetrated each other, the German having its civil population vaccinated optionally, but its army completely re vaccinated, while the French (population and army alike) were vaccinated per functorily. Both were attacked by small pox; but the French army numbered 23, 000 deaths by it, while the German army had only 278; and in the same tent, breathing the same air, the French wounded were heavily visited by the dis ease, while the German wounded, having been revaccinated, had not a single case. Bizzozero (Med. News, Dec. 17, '98).