58 "- LABOR'ATQRY. BACTERIOLOGY 
EXERCISE’ XVI 
* STAINING SPORES AND-FLAGELLA . 
88. In certain species of bacteria and under suitable condi- 
tions there appear within the bacteria highly refractive bodies 
known as spores. The formation of spores is restricted to cer- 
tain species. The spores are oval in form, and in old cultures 
they may often be found outside of the bodies of, the: organisms 
which produce them. They possess the power of resisting dry-.- 
ing, heat, and unfavorable environment much longer than the 
bacilli themselves. They do not stain by the usual methods 
employed in staining bacteria, so special methods are required. 
Several processes have been proposed, but the one here given 
seems to be quite as efficient as any of the others. 
B. subtilis, or the hay bacillus, is one of the most widely 
distributed species of bacteria. It develops spores which can’ 
be readily detected in either fresh or stained preparations from 
cultures. 
The motile bacteria are provided with a variable number 
of long, hairlike appendages or flagella. These are invisi- 
ble in the fresh preparation, and they do’not stain by the 
ordinary methods. By special staining processes, however, their 
presence can be detected. Several methods have beén pro- 
posed for staining these filaments, but nearly all of them are 
based on the use of a mordant. Curiously enough the value 
of each of these methods seems to rest largely on the skill of 
the individual using them, as some workers succeed with one 
method while others fail with it but obtain excellent results 
with one of the other processes. Although the flagella are 
known to be the organs of locomotion, they do not seem to be 
of any special morphological value in differentiating closely 
related species. ‘They are, however, elements in the structure of 
motile bacteria, and their demonstration is much to be desired. 
