FILTERABLE VIRUSEfi 6:31 
The etiology of acute anterior poliomyelitis was for many years a 
matter of conjecture. In 1909, however, Landsteiner and Popper^ 
transmitted the disease to two monkeys through the injection of a 
saline emulsion of the spinal cord from an acute case. The animals 
developed paralysis of their limbs, and were killed and studied bac- 
teriologically and pathologically. The lesions were similar to those 
found in human cases; the cultures were wholly negative. An attempt 
to introduce the disease in other monkeys by the injection of material 
from two successfully inoculated animals proved futile. They believed 
the virus belonged to the group of filterable viruses. Flexner and 
Lewis'- and Landsteiner and Levaditi^ soon confirmed the filterable 
nature of the virus, and Flexner and Lewis succeeded in transmitting 
the virus through a succession of monkeys. The success of their 
transmission lies in the choice of inoculation site— intracerebral 
inoculations are reliable, but intraperitoneal injections are usually 
barren of results. Of great importance are the observations of Flexner 
and Clark'' and Osgood and Lucas^ that the virus may survive in the 
mucosa of the naso-pharynx of infected monkeys for several weeks. 
Landsteiner, Levaditi and Pastia*^ have established the presence of 
the virus in the tonsils and pharyngeal mucosa of an acute fatal case 
of infantile paralysis. Flexner, Clark and Fraser^ have shown defi- 
nitely that the virus was carried in the upper respiratory mucous 
membranes of healthy human adults, the parents of a child suffering 
from an acute attack of the disease. Kling, Werstedt and Petterson^ 
claim, on the basis of experimental evidence, that the nasal secretion 
may also harbor the virus. Neustaedter and Thro^ have found that 
the virus may remain viable in dust. The transmission of the virus, 
therefore, would appear to be largely through the upper respiratory 
tract. Flexner and Amoss^° have brought forth experimental evidence 
to show that the atrium of infection is the upper respiratory mucous 
membrane, and that the virus travels to the meninges by way of the 
lymphatics; not, as a rule, through the blood. Available evidence 
w^ould indicate that insects play no part, or at best, a very minor 
role in the transmission of the virus. ^^ The observations of Flexner 
and Amoss'2 and of Clark, Fraser and Amoss" would indicate that 
1 Ztschr. f. Immunitatsforschr., 1909, 2, 378. 
2 Jour. Am. Med. Assn., 1909, 53, 2095. 
' Compt. rend. Soc. de biol., 1909, 67, 592. 
* Proc. Soc. Exp. Biol, and Med., 1912, 10, 1. 
5 Jour. Am. Med. Assn., 1911, 54, 495. 
6 Semaine med., 1911, p. 296. 
7 Jour. Am. Med. Assn., 1913, 60, 201. 
8 Ztschr. f. Immunitatsforsch., 1911, 12, 316, 657; 1912, 14, 303. 
9 New York Med. Jour., 1911, 94, 813. 
" Jour. Exp. Med., 1914, 20, 249. 
11 Sawyer and Herms: Jour. Am. Med. Assn., 1913, 61, 461. Clark, Fraser and 
Amoss: Jour. Exp. Med., 1914, 19, 223. Anderson and Frost: Public Health Reports, 
1913, 28, 833. 
12 Jour. Exp. Med., 1914, 19, 411. 
" IjOC cit. 
