554 PATHOGENIC AEROBIC BACILLI 
Pathogenesis.—In Hauser’s experiments filtered cultures (two to six cubic 
centimetres), injected into the circulation or into the cavity of the abdomen 
in rabbits, caused fatal toxeemia. 
PROTEUS ZENKERI. 
Obtained by Hauser (1885) from putrefying animal substances. 
Morphology.—Bacilli which vary greatly in length—average about 1.65 », 
and about 0.4 u broad. 
Biological Characters.—An aérobie and facultative anaérobic, non- 
liquefying, motile bacillus. Spore formation not observed. Grows in the 
usual culture media at the room temperature. Upon the surface of nutrient 
gelatin a laminated mass forms about the point of puncture, from the peri- 
phery of which offshoots are given off, at the extremities of which colonies 
are formed, as in the case of Proteus mirabilis. Gradually a rather thick, 
grayish-white, opaque layer is formed, which covers the entire surface of the 
gelatin and is easily detached from it. This species is distinguished from 
the two preceding by the fact that it does not liquefy gelatin or blood serum 
eee does not give off a decided putrefactive odor when cultivated in these 
media. 
Pathogenesis.—Considerable quantities injected into small animals give 
rise to local abscesses and to symptoms of toxemia. 
PROTEUS SEPTICUS. 
Obtained by Babes (1889) from the mucous membrane of the intestine and 
‘the various organs of a boy who died of septiczemia. 
Morphology.—Bacilli about 0 4 4 broad and varying greatly in length; 
‘slightly curved rods or flexible filaments, often associated in loose chains. 
Stains by the usual aniline colors and by Gram’s method. 
Biological Characters.—An aérobic, liquefying, motile bacillus. Spore 
formation not observed. Grows in the usual culture media at the room 
‘temperature. In gelatin plates centres of liquefaction are quickly formed 
and rapidly extend. The spherical, liquefied places have at first a wavy or 
-dentate outline, and are surrounded by a branching, transparent, granular 
margin which rapidly extends in advance of the liquefaction. In stab cul- 
tures in nutrient gelatin liquefaction of the entire contents of the tube may 
take place within twenty-four hours, or a broad, liquefied sac is formed 
along the line of puncture. Gelatin cultures give off a very disagreeable 
odor. Upon the surface of nutrient agar, at 37° C., a peculiar, thick net- 
work extends over the surface in the course of a few hours. Upon potato an 
elevated, brownish-white, shining layer is formed. Blood serum is lique- 
fied by this bacillus. 
Pathogenesis.—Pathogenic for mice, less so for rabbits. In mice death 
-occurs in from one to three days after the subcutaneous injection of a small 
ee of a pure culture ; the bacilli are present in the blood in small’ 
numbers. 
PROTEUS LETHALIS. 
Synonym.—Proteus bei Lungengangran des Menschen (Babes). 
Obtained by Babes (1889) from the spleen and gangrenous portions of the’ 
lung of aman who died of septicaemia. 
Morphology.—Short rods with round ends, from 0.8 to 1.5 u thick ; often’ 
‘swollen in the middle, like a lemon ora flask ; forms short, flexible filaments 
which also present similar swellings. 
Stains with the usual aniline colors and also by Gram’s method. 
Biological Characters.—An aérobie’ and facultative anaérobic, non- 
liquefying, motile bacillus. Net observed to form spores. Grows in the 
usual culture media at the room temperature. In gelatin plates forms hemi- 
spherical, elevated, whitish, translucent colonies, which later send out 
