394 



THE DOUBLE STAINING OF SPORES AND BACILLI. 



By R. Greig Smith, M.Sc, Macleay Bacteriologist 

 to the Society. 



Until quite recently the methods recommended by various 

 authors for staining the spores of bacilli produced results that 

 were far from being satisfactory. Fortunately this state of 

 affairs has been removed by Klein*, of Amsterdam, who has 

 published a method which, with a little improvement, is eminently 

 successful. 



The methods in general use consist in the first place in preparing 

 a film of the material to be stained by mixing a portion of an 

 agar or potato culture of the bacillus with a drop of water upon 

 a clean cover-glass and allowing the suspension to dry. The 

 dried film is then fixed by passing it three times through the 

 bunsen-tiame, a process which has for its object the coagulation 

 of the bacterial protoplasm and the attachment of the bacteria to 

 the glass. From this point the methods differ. The spore-case 

 or capsule which prevents the entrance of the stain within the 

 spore is destroyed more or less by attacking it with physical or 

 chemical agents. The physical treatment consists in heating the 

 film in the air-bath for about half-an-hour at 200° C, or in the 

 autoclave at 120° C, or even by passing the film many times 

 through the bunsen-fiame. The chemical manipulation involves 

 the treatment of the film with strong sulphuric acid, potassium 

 hydrate, zinc chloriodide, 5% chromic acid or \°/ hydrochloric 

 acid. These methods are employed to soften the spore-capsule 

 after it has been hardened by the process of fixation. Klein had 



* Centralblatt fur Bakteriologie, i. Abt. xxv. 376. 



