NOT DESCRIBED IN PREVIOUS SECTIONS. 553 
rapidly as Proteus vulgaris. Upon gelatin plates, at the end of twelve 
ours, superficial colonies of two to three millimetres in diameter are formed; 
under a low power these appear finely granular and brownish in color, and 
have an irregular outline; outgrowths from the margin extend in various 
directions and form new colonies, which may be attached for a time by a 
long and slender thread consisting of bacilli. The movement of these new 
colonies is not as pronounced as in the case of the preceding species, and 
Fie. 155.—‘‘ Swarming islands *’ of Proteus mirabilis, from a gelatinculture. x 285. (Hauser.) 
they are characterized by the presence of numerous distorted bacilli—invo- 
lution forms. The deep colonies form spiral zodglcea masses. 
In gelatin stab cultures the whole surface is first covered with threads 
and islands of bacilli, which after atime form an anastomosing network, and 
finally a confluent layer which at the end of forty-eight hours is rather thick, 
Fia. 156.—Spiral zodglosa from a culture of Proteus mirabilis. x 95. (Hauser.) 
with a moist, shining surface and grayish color, and appears to be perforated 
with numerous small, sieve-like openings. These thinner and transparent. 
places disappear after a time, and at the end of two or three days liquefac- 
tion of the gelatin commences; complete liquefaction does not occur until 
the fifth or sixth day, or even later. Along the lineof puncture finely gran- 
ular colonies are first formed, from which long threads are given off, which 
form after a short time a tolerably broad zone of threads and spiral zodgloea 
masses. 
