DISEASES OF UNKNOWN ETIOLOGY 659 
twenty-four hours after the inoculation. The reddened area fades 
rapidly and the entire process heals almost as quickly as the simple 
reaction of trauma excited by the scratch in the epidermis. The 
accelerated and immediate reactions are usually regarded as poten- 
tially eqiii\'alent to a typical reaction, provided they are induced by 
revaccination. 
Mumps.— ]\Iumps or epidemic parotitis is a specific infectious 
disease which is more commonly observed among children from four 
to fifteen years of age, although yoimger children and adults are by 
no means immune. The incubation period averages from seventeen 
to twenty-eight days. It is probable that the infectious period beigns 
a few days— about four— before the characteristic syndrome appears, 
and the disease is probably transmitted directly from person to per- 
son through infected material from the naso-pharynx. The mortality 
is very low and cases that terminate fatally are generally very }'oung 
children and infants. 
The causative agent is not definitely known: a diplococcus has been 
isolated from inflamed parotid glands by Laveran and Catrin^ in 
67 out of a total of 92 cases. Mecray and Walsh,- Michaelis and 
Bienn,^ Busquet and Feri* have made similar isolations. Teissier 
and Esmein^ report the successful culture of a similar organism from 
a case of suppurative parotitis. Herb^ also has isolated a diplo- 
coccus from a case of suppurative parotitis which ended fatally. 
Animal experiments with these cultures have not been convincingly 
positive. 
Nicolle and C'onseille^ and Gordon,^ working independently, state 
that fluid separated from the parotid glands of patients having mumps, 
injected into the parotid glands of monkeys, reproduced a syndrome 
strikingly like that of mumps in these animals. Gordon also found 
that the \irus retained its virulence after passage through a Berkefeld 
filter. It is destroyed by a brief exposure to 55° C. It would appear 
from his observations that the virus of mumps belongs to the group 
of filterable viruses. 
1 Compt. rend. Soc. de biol., 1893, 45, 95, 528. 
2 Med. Rec, 1896, 50, 440. 
3 Verhandl. XV Kongress f. inn. Med., 1897, 15, 441. 
4 Rev. d. Med., 1896, 16, 744. 
5 Compt. rend. Soc. de biol., 1906, 60, 803, 853. 
6 Arch. Int. Med., 1908, 4, 201. 
' Compt. rend. Acad. Sci., 1913, 157, 340. 
8 Lancet, 1913, ii, 275. 
