22 NOTES ON MICRO-ORGANISMS, 
and Bacterium amylobacter (Plate I., Fig. 5, and Plate II., 
Fig. 2). 
I find in my sketch book two very good instances of sporulating 
Bacteria, one (@) growing in brewers’ grains after a cultivation of 
mould, the other (4) in a mass of ground rice used for the same 
purpose (Plate II., Fig. 3). In both cases the Bacteria were 
found underlying the mould growths, where they must have been 
formed out of free contact with air. One was most probably 
Bacterium lactis, and the other Bacillus subtilis. It is very easy 
to obtain the latter in a spore-bearing state from hay infusions, as 
before pointed out. After an active growth of the Bacillus, 
sporulation generally takes place. I should like to remark here 
that, although the conditions in beers are rather favourable than 
otherwise to spore formation, I do not recollect having seen in 
them any of the rod or thread Bacteria in a sporulating state. 
Bacteria under certain circumstances develope a very curious 
condition known as the Zoogloea, or resting state, caused by the 
reproduction in close proximity of swarms of Bacteria (Plate II., 
Fig. 4) with a gradual withdrawal of nourishment. Owing also 
to a tendency that the organisms have to increase the enveloping 
membrane, which at the same time becomes gelatinous; and this 
may proceed till the contour of the separate cells is almost lost, 
and sometimes an almost indistinguishable mass remains where 
formerly well defined Bacteria were seen. 
To proceed to some of the more general phenomena associated 
with the growth of micro-organisms. The production of a definite 
pigment (as in the case of Micrococcus aurantiacus) is a property 
belonging to a fairly large class called Colour Bacteria, producing 
a considerable variety of pigments, amongst which crimson, 
scarlet, violet, and yellow are included. The Bacterium form is 
in most cases a small sphere, varying somewhat in size and 
appearance, though in some cases the colour produced is the only 
means of identification. Some of the colours are so vivid that 
the question arises in one’s mind as to whether some commercial 
application of the property of these organisms could not be 
devised. Colour Bacteria can easily be obtained from slices of 
