A Contribution to the Morphology of Bacteria. 
By 
E. Klein, M.D., F.R.S., 
Lecturer on General Anatomy and Physiology at St. Bartholomew’s 
Hospital Medical School. 
With Plate 1. 
Since the classical papers on Bacteria published by Pro- 
fessor F. Cohn in the ‘Zeitschrift der Biologie d. Pflanzen,’ 
vols. i to ili, all bacteriologists have accepted the subdivision 
of the Schizomycetes into cocci, bacilli, and vibrios or spirilla, 
as representing the main morphological fundamental types. But 
by Lankester! and Zopfs’ researches on Cladothrix dicho- 
toma, and by Hauser’s well-known and exhaustive work 
on ‘ Putrefactive Bacteria’ (‘ Ueber Faulnissbacterien,’ Leipzig, 
1885), it has become recognised that the shape under which a 
particular bacterial species presents itself depends both on the 
medium in which it grows, as also on certain inherent charac- 
ters of the organism itself. Thus it has become recognised 
that while the elements of one species appear as often in the 
form of oval as of cylindrical cells, those of another retain, 
under almost all conditions, pre-eminently that of cylindrical 
cells. To name a few instances: (a) the Proteus vulgaris 
of Hauser. This organism—the organism of putrefaction par 
ex cellence—is known to occur in the most varied shapes, as 
cocci, oval forms, cylindrical and vibrionic forms; but when 
growing in gelatine plates at 20° C. it will be found that in the 
1 ¢ Quart. Journ. Micr. Sci.,’ vol. xiii, 1873; vol. xvi, 1876. 
VoL. 36, PART 1,—NEW SER, A 
