THE BACTERIACEA. 169 
poisoning, pyzeemia and septicemia. In the genus Bacterium, of 
Cohn, we find the well-known JS. ¢ermo, the most energetic of the 
saprophytes, found in many putrescent substances, and especially 
in macerations of muscular tissue, where they appear as oblong 
cells, about 14 to 2 yw long, with a flagellum at each end. Amongst 
the pigment-forming species of this genus are two, morphologically 
identical, which produce the so-called “yellow” and “blue” 
appearances of sour milk. The genus Sarcina is best known by 
S. ventricult, found in the stomachs of man and other animals in 
health and disease ; the individual cells sometimes attain a diameter 
of 4 w. Other species are found in the bladder and kidney. The 
genus Bacillus, in its saprophytic character, is found plentifully in 
vegetable infusions. B. sudéilis is the agent of butyric fermenta- 
tion and the ripening of cheese, and is found abundantly in in- 
fusions of hay; cells usually as large as 6 mw long, a flagellum 
at eachend. The well-known pathogenic species, B. anthracis, the 
cause of splenic fever (anthrax) in cattle and sheep, and of “‘ wool- 
sorters’ disease” (pustula maligna) in man, belongs to this genus; 
cells 4 » long and very slender, without flagella. The more recently 
discovered &. tuberculosis (Koch) of pulmonary consumption has 
its place in this genus. The genus Leptothrix, some of the species 
of which are evidently phycochromaceous alge, consists of colour- 
less and motionless threads, and in one species these threads attain 
a length of 100 to 140 w by 1 » wide. Beggiatoa is found mostly 
in sulphur hot-springs, where it decomposes the sulphur compounds 
and liberates sulphuretted hydrogen ; filaments actively oscillating 
and thicker than in Leptothrix. Some species are found in sea- 
water and marshes. It is doubtful whether Vibrio and Spirillum 
are distinct genera, since the discovery of flagella on the former, 
the latter only having previously been supposed to possess them ; 
bent or spirally twisted filaments with a flagellum (in Spirillum) at 
each end ; length and thickness variable ; found as saprophytes in 
various infusions of organic substances, and in the putrefying water 
of bogs and ponds, Spirocheeta is distinguished from Spirillum by 
the greater number and closeness of the spiral turns, and the long 
and slender threads. ‘The species are saprophytic, like Spirillum ; 
one is pathogenic and is found in the blood during the febrile stage 
only of intermittent fever, disappearing during the intervals of 
freedom. 
Reproduction by spores has been observed in Bacterium, Bacillus, 
Spirillum and Spirocheta ; and these genera and Micrococcus are 
sometimes found in zooglcea masses. 
For a more detailed account of the various species into which 
Cohn and other authors have divided the genera, I would refer 
the reader to Hardwicke’s “Science Gossip ” for 1882-3, where he 
will find ‘‘ Notes on the Schizomycetes,” communicated by Mr. W. 
