BABIES. 241 



Notes on Pasteur's Methods of Vaccination. (Preventive 

 Inoculation.) Pasteur made a series of very remarkable observa- 

 tions which have led him to recommend a special method of prophy- 

 lactic inoculation of rabid virus. The observations which he made 

 were as follows: 



1. The rabid poison is most concentrated and purest m the brain 

 and spine. 



3. If the brain is the particular seat of the rabid poisoning, the 

 affected animal has furious rabies. If the spine is affected the 

 most, we see the quiet (or dumb) form of rabies. i 



3. After direct inoculation of rabic poison on the brain-surface, 

 under the dura mater (intracranial inoculation), the disease 

 appears much more rapidly than it does from cutaneous or sub- 

 cutaneous inoculations. With direct brain inoculation the disease 

 may appear in from six to ten days. 



4. After cutaneous or subcutaneous inoculation of the poison 

 the rabid symptoms appear after a much longer time, and seem to 

 depend on the fact that the further the- inoculated region is from 

 the brain the longer it takes to develop the disease. 



5. The disease appears more rapidly if the virus has been intro- 

 duced directly into the circulation than cutaneously or subcuta- 

 neously. In the latter case it generally takes the form of quiet or 

 dumb rabies. 



6. We can never expect any good termination when the symp- 

 toms are very violent in the early stages of the disease. An injec- 

 tion of blood or saliva of a rabid animal into the veins does not 

 as a rule terminate fatally, but at the same time it does not 

 appear to protect an animal, in the future especially, if it is 

 inoculated again under the dura matter with rabid virus. 



7. The intensity of the poison may become very much modified 

 by inoculation through the medium of other animals. After a 

 series of generations of inoculation through different monkeys, it 

 is much weakened and does not produce- rabies in dogs, either by 

 subcutaneous or intracranial inoculation, but this "weakened" 

 virus, if injected into the dog, renders the animal proof against 

 further inoculations of the most active virus. On the other hand, 

 rabid virus increases in intensity if it is inoculated from one rabbit 

 to another, and the period of incubation is lessened until the dis- 

 ease shows itself positively in seven days. By experimental trans- 



