With regard to virus infections of the nervous system, generalizations are of limited validity. In the study of any single disease, plurality of strains of the virus, relative susceptibilities of various experimental animal species and differences between natural and experimental hosts offer serious complications. And different diseases seem to behave in quite different fashion. Only isolated data are available, and inferences can be suggested rather than proved.
With this word of caution, three arbitrarily selected topics may be critically examined.
THE SIGNIFICANCE OF THE NASAL PATHWAY IN INFECTION
The possible importance of the nasal pathway in poliomyelitis has received the attention of investigators for many years. In 1912 Flexner and Clark1 showed that monkeys might be experimentally infected by the application of virus into the nose and that in such cases the virus localized first in the olfactory bulbs. Faber and Gebhardt2 demonstrated the the orderly progression