NOTES ON MICRO-ORGANISMS. 19 
Class III.—Desmo-bacteria ... ... Threads. 
,, [V.—Spiro-bacteria ... ... Spirals. 
Class I., generally known as the coccus or micrococcus form, 
propagates usually by simple division in two or more directions. 
This is very well shown by an organism—Sarcina litoralis— 
(Plate II., Fig. 1) found in putrefying sea water. Another coccus 
form, but not a true micrococcus, is brought about by the 
breaking up of longer or shorter rod lengths into ovals and 
spheres, by constriction of the outer envelope at given points. 
Several of the micrococci connected with interesting though pain- 
ful complaints that men and animals are liable to, are probably 
reproduced in this way. 
Separated pairs, as in the case of Bact. aceti (Plate I., Fig 2), 
are calied Diplococci. 
Budding of one spherical cell out of another has not, so far as 
I know, been observed in connection with Bacteria. 
The normal methods of reproduction of Classes II. and III. 
are—(a) by the continuous development of rod lengths, (4) by 
the formation of spores capable of germination and reproduction 
of the Bacterium form. I have selected Cladothrix dichotoma as 
an illustration of rod lengths, showing at the same time what is 
called false-branching (Plate III., Fig. 1), and as examples of 
spore formation :—Bacterium amylobacter (Plate II., Fig. 2) and 
Bacillus subtilis (Plate I., Fig. 5). 
The spirillum forms of Class IV. are, with exception of sporu- 
lation, produced in a very similar way, sometimes in short lengths, 
sometimes in very long pieces, which afterwards break up into 
separate individuals. 
According to Cohn, all Bacteria tend to reproduce a constant 
and uniform type, Micrococcus yielding Micrococcus, and 
Spirillum, Spirillum ; but if Zopf’s more recent researches be 
accepted, this position is no longer tenable, for Zopf shows clearly 
that with many Bacteria long rod lengths may produce short ones, 
and even coccus forms, in fact, almost every form assumed by 
these organisms at all. Plate II., Fig. 5 Bacterium merismope- 
dioides — shows all forms but the spiral, whilst Cladothrix 
