CHAPTER IX. 



THE STAINING OF SPORES, CAPSULES AND FLAGELLA. 

 THE STUDY OF THE MOTILITY OF BACTERIA. 



Section I. Spores, p. 145. 



1. The examination of unstained preparations, p. 145. 2. The staining of spores, 

 p. 146. 



Section II. The staining of capsules, p. 147. 

 Section III. The staining of flagella, p. 148. 



1. The staining of flagella in living organisms, p. 148. 2. The staining of flagella 

 in dried preparations, p. 149. 

 Section IV. The methods of studying the motility of micro-organisms, p. 154. 



SECTION I. SPORES. 



WITHIN the protoplasm of certain micro-organisms, a small bright refrac- 

 tile spot is seen at one period or another of their existence. This refractile 

 body, which does not stain readily with the ordinary aniline dyes, is known 

 as a spore, or more strictly an endospore. The occurrence of spores was 

 first described by Pasteur. 



On the death or destruction of a spore- bearing organism the spores are set free 

 from the protoplasm in which they originated. They are surrounded by a highly 

 resistant membrane, which not only renders them immune to the agents ordinarily 

 destructive of bacteria, but also prevents them becoming stained by the methods 

 generally employed for staining micro-organisms. 



Endospore formation does not occur in all bacteria : it is unknown in the 

 micrococci, in which the resistant form is due to a thickening of the enveloping 

 membrane and is known as an arthrospore. Arthrospores differ from endo- 

 spores in that they react to stains in the same way as do their corresponding 

 organisms. 



It is therefore only necessary to describe the methods of staining endospores. 

 The organisms more commonly used for illustrating the methods are the 

 Bacillus anthracis, Bacillus megatherium, Bacillus maligni oedematis, Bacillus 

 tetani, and Bacillus subtilis. 



1. Examination of unstained preparations. 



In unstained preparations the spore appears as a small, refractile, spherical 

 or oval spot within the protoplasm of the cell ; it is surrounded by a bright 

 refractile ring, and is always smaller than the mother cell. The mother 

 cell gives rise to a single spore which becomes free on the disappearance of 

 the cellular protoplasm ; the spore in turn germinates, giving origin to a 

 new bacterium. 



