No. 4.] CATTLE COMMISSIONERS. 487 



are left on the cotton, instead of passing through it. If too much 

 water is added at first, it is almost impossible to grind the powder, 

 and it becomes necessary to place the mortar, with its contents, in 

 a warm and airy place, in order to allow some of the water to 

 evaporate. Only sufficient water should be added to the powder 

 to make it form a paste, in which form it is easy to grind it ex- 

 tremely fine. 



When a large number of animals are to be vaccinated at the 

 same time, three or four packets of the vaccine may be dissolved 

 at once, care being taken that the requisite amount of water is 

 used, as otherwise the solution will be too strong or too weak. 

 When the vaccine is prepared at home, a small sterilized medicine 

 bottle may be substituted for the measuring glass under the funnel. 

 The stopper of this bottle, if cork, must have been thoroughly 

 soaked in boiled water. The vaccine is carried in the bottle to the 

 place of operation, where it may be transferred, a little at a time, 

 to the measuring glass ; from this it may conveniently be drawn 

 into the syringe. In doing this it is of importance to remember 

 that, when standing for some time, a slight sediment will form at the 

 bottom of the vessel or bottle, and the vaccine should therefore 

 always be well shaken or stirred before the syringe is filled. When 

 some time elapses between the vaccination of two animals, and the 

 syringe still contains one or more doses of vaccine, the operator 

 should turn the syringe up and down frequently to insure an even 

 distribution of the germ-carrying particles throughout the vaccine. 



No more vaccine should be prepared at one time than can be 

 used the same day. While the vaccine powder will remain un- 

 changed for some months, the solution deteriorates very quickly, 

 and must be used within twenty-four hours after it is made. 



Animals to be vaccinated. 



Calves, as a rule, should not be vaccinated until they are six 

 months old. Under this age they are practically immune from 

 blackleg, and it has been claimed that when vaccinated before they 

 are six months old they are liable to lose the artificial immunity 

 induced by means of vaccination, and become susceptible again. 

 Animals more than two years old are seldom affected, and the 

 mortality among them is so small as to make vaccination unprofit- 

 able. It is the calves between six months and two years old which 

 should be vaccinated. Vaccination has no ill effect on calves 

 under six months old ; but it should be a rule that when very 

 young animals are vaccinated they should be revaccinated before 

 the beginning of the following blackleg season. 



