Armstrong – Table of Contents

Hg.). 4) Centrifugation at high speed for 15 minutes (designed to precipitate ordinary
bacteria) failed to remove the infectious agent from spinal fluid and brain suspensions,
although there was evidence of diminution of the amount of virus. 5) Monkey and mouse
strains were found to retain their infectivity for at least 206 days when stored at 4-10C in
50 per cent glycerine in 0.85 per cent saline. 6) A temperature of 55-60C for 20 minutes
destroyed the infectivity of brain suspensions for mice. 7) He did not find cell inclusions,
found in some viral diseases, in histological sections. The above criteria, standard for the
time, thus indicated to Armstrong that he was dealing with a virus.
Further studies showed that rhesus and cebus monkeys, white mice, wild mice, and
guinea pigs were susceptible to infection by intracerebral inoculation. White rats and
rabbits were not found susceptible by this route.
He also described in detail the physical signs of illness in monkeys and white
mice. Monkeys, unless sacrificed, usually survived the infection; the mice invariably died
in convulsions. Standard features of the spinal fluid in monkeys were increased pressure,
clear fluid and cell counts varying from 150 to 1,260 cells per cu. mm., almost entirely
lymphocytes. White blood cell counts, while the monkeys were ill, varied from 10,000 to
19,400 cells per cu. mm. without constant differential counts.
Armstrong, in studying the distribution of virus in the tissues of monkeys during
the febrile attack by mouse transfer, regularly found the agent in the brain, spinal fluid,
blood and in a single demonstration in urine collected at autopsy. He also demonstrated
the virus in the blood and brain of mice.
In addition to intracerebral inoculation, Armstrong demonstrated other
experimental routes of infection in monkeys. He was able to infect monkeys with the