G8 The Farmer's Yeterinary Ad/viser. 



system, and too often in their distribution on surrounding 

 objects, where tliey maybe preserved indefinitely to infect 

 other susceptible animals. As in the case of all germs, there 

 is the certainty of reversion to the original deadly type when- 

 over the .medium in which they grow is favorable to such 

 transition. Pasteur himself has shown this to be the case, 

 when his weakened antlirax virus is passed through a suc- 

 cession of young guinea-pigs ; and what is true of one germ 

 is true of all in this respect. All have the power, within 

 given limits, of adapting themselves to varying conditions 

 of life. That the weakened virus (misnamed vaccine) has 

 the power of reversion to the deadly type is assured to us 

 by the fact that already a cliange of culture has robbed it of 

 its deadly potency without destroying its life ; it has merely 

 acquired a new habit of life, and the recurrence to the origi- 

 nal habit is just as certain undei- a reversal of the condi- 

 tions. ISTothing, then, short of the absolute seclusion and 

 disinfection of the inoculated animals, and their habitations 

 and belongings, will render such inoculations reasonably 

 safe. With the use of sterilized vii-us, on the other hand, 

 all sucli possibilities of diffusion of the disease-germ are en- 

 tirely done away with. 



1st. 'No living gerra is introduced into the animal sys- 

 tem. 



2d. No multiplication of germs can occur on nor in the 

 animal. 



3d. Tlie inoculated animal can convey no living germs to 

 surrounding objects. 



4th. Tlie material inoculated agrees with ordinary chem- 

 ical poisons in affecting the system only in ratio with the 

 dose. It has no power of self-multiplication, with conse- 

 quent augmentation of its power for evil. 



5th. The dose can be graduated as easily and safely as 

 can a dose of morphia. 



6th. By a succession of small doses we can keep up the 



