236 Ellis . — The Life- history of Bacillus hirtus . 
the oblong, but as all parts are not in focus, it appears somewhat distorted. 
The structure of the spore is therefore normal, and the occurrence of the 
bluntly pointed ends is common enough to make it not of much value for 
purposes of diagnosis. 
Germination of the Spore. 
To observe the germination, the spore-material was sown very thickly 
over the surface of the Agar in an Agar-tube, which was then placed in an 
incubator (33" C.) and examined at various times. Even after three hours 
some spores had germinated, but the most favourable period for their 
examination is after 6-7 hours, when a very large number of germinated 
spores can be observed. This facilitates the task of observing the various 
stages in the germination. As in all observed cases, the first sign of 
germination is a swelling up of the whole spore, doubtless due to the 
absorption of water, with a consequent loss of its very strong refractive 
power. By observation of Figs. 7-9, it will be seen that the vegetative cell 
issues from the equator of the spore. I could not observe a single case of 
polar germination, and believe that equatorial germination is constant for 
this species. When observed after three hours, in several cases cell-division 
had already taken place (Figs. 8-9), but in no case were any vegetative cells 
present, unattended by the spore-membrane. The stages of germination 
can be seen by comparing Figs. 7-9. First a swelling of the spore, then 
very soon afterwards a splitting of the exine at the equator take place. 
Next the young vegetative cell protrudes through the split, and in many 
cases cell-division takes place (Fig. 8) when the young cell is still attached 
to the spore-membrane. To observe the further development, the culture 
was examined after five hours, when a comparatively thick though transparent 
layer is seen on the surface of the Agar. Cell-division has now proceeded 
much further in the advanced stages, the spore-membrane has been dis- 
carded, and examples similar to those represented in Fig. 10 are com- 
paratively common. In this culture these threads of two-celled individuals 
were almost exclusively present (an individual is distinguished from a cell 
in that no account is taken of any transverse cell-walls that may be present, 
regard is paid merely to the entity, thus Fig. 9 is an individual consisting 
of two cells , Fig. 15 a is an individual consisting of four cells). Even at this 
stage there is a trembling movement which infers the possibility of movement 
apart from molecular movement. This subject is discussed more fully 
under the heading ‘ Motility.’ It is sufficient to mention here that as there 
are indications of motility even at this early stage, the young individuals 
soon free themselves from the trammels of the spore-membrane and life in 
the next generation has begun. 
In connexion with the germination of the spores, it would be inter- 
esting to know the fate of the intine. Is it cast off with the exine or does 
