1388 BACTERIOLOGY. 
In what other ways do bacilli grow ? 
Beside the power of increasing by direct division a large number of 
varieties possess the power of forming within themselves little bodies 
called spores. These spores might be said to hold the same relation to 
bacteria as do seeds to more highly organized plants. 
How is the spore formed ? 
The protoplasmic contents of the bacterial cells concentrates at 
certain points, which appear darker and of a different refracting power 
than the surrounding material. These points coalesce to form the 
spore, while the rest of the cell becomes clear and of a light color. 
What is the appearance of a spore? 
It is oval or round, very highly refractive and has a glistening 
appearance. At first it may be surrounded by a layer of clear fluid 
and the outer wall of its parent cell. This wall and the contained 
fluid finally disappear leaving the spore free. 
Why does a bacillus at one time increase by fission and at another 
by spore formation ? 
It is thought that when favorably situated the organism increases 
by fission, and that when altered conditions are present, such as lack of 
nutriment, unfavorable temperature, etc. that spore formation 
begins as a means of self-preservation of the species ; for the spores are 
more resistant to outside influences than are the bacilli, 
Is there a limit to the kind of spore produced by a given bacillus? 
Yes. A bacillus can produce but one kind of spore, and a spore 
but one kind of bacillus. 
To what does the spore owe its power of resisting outside influences? 
To a dense, thick wall called the spore membrane or skin which 
surrounds it. 
How are bacilli produced from spores? 
The spore begins to lengthen and its outline becomes rather indistinct. 
The spore skin seems to swell until finally, as the lengthening process 
goes on, it becomes ruptured and a young bacillus is set free. This 
ruptured membrane soon dissolves and disappears. 
What is the above variety of sporulation called ? 
Endosporie sporulation. 
What is arthrosporic sporulation ? 
A given organism takes upon itself the properties of a permanent 
