610 BACTERIOLOGY. 
Stains readily with the ordinary aniline dyes, but 
not by Gram’s method. 
Biological Characters. A motile, facultative anaéro- 
bic, non-liquefying bacillus. Does not form spores as 
far as known. Grows readily in all the ordinary cul- 
ture media, at the room-temperature, but best at 37° C. 
in the incubator. On gelatin plates it forms rounded 
colonies, transparent and granular It never liquefies 
gelatin. In bouillon the bacillus grows quickly, without 
forming either a pellicle or deposit. On blood-serum 
its growth is almost imperceptible. Cultures on agar 
-are characteristic, according to Sanarelli. When the 
colonies grow in the incubator they present an appear- 
ance that does not differ from many other species; they 
are rounded, of a slightly iridescent gray color, trans- 
parent, even in surface, and regular in outline. Grown 
at the room-temperature from 20° to 22° C., they ap- 
pear like drops of milk, opaque, projecting, and with 
pearly reflections, completely distinct from those grown 
in the incubator. These different modes of evolution 
Sanarelli considers to be an important diagnostic point; 
first exposing the cultures for from twelve to sixteen 
hours to the temperature of the incubator, and after- 
ward for twelve to sixteen hours more to the tempera- 
ture of the air. 
The bacillus icteroides ferments glucose and sacch- 
arose, but does not coagulate milk; produces little 
indol, and is quite resistant to desiccation; it dies in 
water at 60° C., or after being exposed for seven hours 
to the sunlight, and lives for a long time in sea-water. 
Pathogenesis. It is pathogenic for the greater num- 
ber of the domestic animals; but birds are completely 
refractory. According to the discoverer the dog lends 
