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7. The best or perfect material for vaccination appears to be that 
which contains spores only. This is probably due to the small 
quantity of the virus, and to its slower rate of increase. 
8. Interior or imperfect materials for vaccination are more power- 
ful in their action. Thus opaque vaccine and variolous lymph not 
unfrequently produced eruptions, with a modified imperfect local 
effect. Cultivation of clear lymph in solid media appears to in- 
crease its potency, as shown by its production of an eruptive fever 
in a calf. Cultivation of vesicular variolous lymph in solid media 
does not appear to differ in potency from vaccine cultivations, as 
shown by the effect of inoculation on a monkey. The action of the 
material containing spores is probably milder. 
9. Vaccination probably protects from small-pox, by producing 
a mild form of fermentation in the blood. The process probably 
takes place slowly, as the ferment is growing in unsuitable soil. 
10. When the spores or mature forms are inhaled they probably 
grow in the air-passages with extreme rapidity, and thus get into the 
blood, where they multiply during the incubative period. 
11. My observations appear to show that what is called “ attenua- 
tion of a virus ” may be explained by spore-production. Are not 
the perfect vaccine materials for infective diseases to be found in 
the spores of the micro-organisms which are their exciting causes 1 
Bibliography. 
Bary, De. Vorlesungen ueber Bacterien, 1885. 
Blane, Sir Gilbert. Estimate of the true Value of Vaccination, Lond., 
1819. 
Braid wood and Vaciier. Brit. Med. Jour., First, Second and Third Reports 
on the Life History of Contagion, 1875, 1876, 1877, 1878, and 1881. 
Brown, Thomas. I. Inqniry into the Antivariolous Power of Vaccination, 
1809. II. Letter in reply to the Report of the Surgeons of the Vaccine 
Institution, Edin., 1809. III. Letter concerning the Present State of 
Vaccination, Edin., 1823. 
Buchanan, George. On Vaccination, Animal Vaccination, and Small-pox, 
Reports of Med. Officer of Privy Council and Loc. Gov. Board. 
Buchner. Die Umwandlung der Milzbrand-Bacterien in unschadliche 
Bacterien und die Entgegnung R. Koch’s an Pasteur, Birch. Archiv, 
vol. xci. 1883. 
Burdon Sanderson. Intimate Pathology of Contagion, Reports of Local 
Government Board. 
Cameron, Charles, M. P. Anti-Cholera Inoculation, Nineteenth Century, 
Aug., 1885. 
