254 INFECTIVE DISEASES. 



patients and in the buboes are not identical. The bacilli in the 

 buboes are different in form, and they stain by Gram's method. 



There is no doubt that the micro-organism which was found in 

 blood is very similar to the bacillus of fowl cholera, and it is quite 

 possible that the so-called plague bacillus is really identical with the 

 bacillus of haemorrhagic septicaemia, and that the real nature of the 

 contagium in bubonic plague is unknown. 



Protective Inoculation. — Yersin, Calmette, and Borrell claim 

 not only to have produced immunity, but to have cured animals 

 after infection. Cultures on agar heated to 58.° 0. for an hour 

 were attenuated, and rabbits after intravenous or subcutaneous 

 inoculation were protected against virulent cultures. The serum 

 of immunised rabbits was capable of protecting from subsequent 

 virulent cultures, and neutralising the effect of a previous inoculation 

 of a virulent culture. A horse was inoculated with cultures which 

 killed mice in two days, and after six weeks a serum was obtained 

 which produced immunity in mice and guinea-pigs. 



Stamping-out System. — It is not until the sixteenth century 

 that we hear of preventive measures being attempted in England, 

 and then they appear to have been adopted only when an outbreak 

 threatened to be very serious. 



Early in the sixteenth century all those who had the plague in their 

 houses were ordered to put up wisps, and to carry white rods in their 

 hands. 



In 1643 the Plague Order of Henry VIII. was issued. In place of 

 wisps the sign of the cross was to be made on every infected house, and 

 to remain there for forty days. Persons afHicted with the disease were 

 to refrain, if possible, from going out of doors, or for :^orty days to carry 

 a white rod in the hand. All straw from the infected houses was to be 

 carried into the fields and burnt. Churchwardens were directed to keep 

 beggars out of churches on holy days, and all streets and lanes were to 

 be cleansed. 



In 1547 the means of notification was a blue cross with the addition 

 of the inscription Lord have mtrcy wpon us. Later on the colour of the 

 cross was changed to red. 



With the outburst of the plague in 1563, came an attempt to enforce 

 a terrible system of compulsorily shutting up infected families. The 

 doors and windows in such houses were to be closed, and no inmates were 

 to leave the premises and no visitors to be allowed for forty days. No 

 better incubator on a large scale could possibly have been devised for 

 both breeding and intensifying the virulence of the plague bacillus, or 

 whatever may be the contagium vivum of this disease. 



This compulsory shutting up of the sick with the healthy amounted 

 to a compulsory infection of many of the unfortunate inmates who might 



