241 
Ellis . — The Life-history of Bacillus hirtus. 
encroached on the white, till after ten days the lower half was white and the 
upper half bronze-coloured. This fleshy crinkled growth in this species is 
not normal for growth in Agar-tubes. Microscopically there was nothing 
remarkable except a diminished formation of spores. As a matter of 
experience I have found that a fleshy growth is almost always associated 
with a diminution or absence of spore-formation in those forms which 
habitually form spores. With regard to the bronze-coloured colonies and 
bronze-coloured Agar-tube cultures, they retain their colour for at least 
a year, but when inoculated into a fresh tube, the colour of the new 
generation is again normal. 
Gelatine Stab-Cultures. 
It is as useless giving any particulars of the rate of growth of 
a gelatine stab-culture for diagnostic purposes as for a gelatine plate-culture, 
for having made them at different times of the year, using tubes which 
necessarily did not belong to the same preparation, I have never obtained 
uniform results. Henrici records a rapid growth. In my cultures growth 
was oftener extremely slight. In Fig. 13 is shown a drawing of a gelatine 
tube after three months. Fig. 14 shows another gelatine stab-culture only 
three days after inoculation. The liquid part had a yellowish-brown 
colour, was turbid, and had a thick deposit at the bottom of the liquid. 
Lower down, the continuation of the stab showed a few small round 
colonies each with fine radiating branches. In a few days after this the 
gelatine became completely liquefied. In a third experiment, about half 
the gelatine had become liquefied only after two months. In all cultures a 
constant feature was the appearance on the surface of a light grey speck. 
Sometimes it increased rapidly in size, but oftener growth was exceedingly 
small. Along the stab there was a very scanty growth, showing its strong 
aerob tendency. The surface growth extends into a roughly circular 
greyish-white covering on the top of the gelatine. At some time or other 
liquefaction always sets in, provided that the organisms are still alive. 
Usually the liquefied part has, in suspension, a very fine flocculent greyish- 
white precipitate. If growth proceeds filter-fashion as in Fig. 13, there 
is a thick sediment at the bottom of the filter-tube. The same happens 
when the whole of the gelatine has been liquefied. I examined the 
individuals of a gelatine tube, in which the gelatine had taken four months 
to liquefy completely, and found them perfectly healthy, but there was 
no spore-formation. 
Growth in various Liquid Media. 
As a further help in diagnosing this species various liquid media were 
prepared, because Bacteria in the assimilation of N and C differ in the mode 
of combination of these substances which best suits them. The various 
