146 BACTERIOLOGY. 



GLACIAL ACETIC ACID METHOD. Another method 

 which may be employed for demonstrating the presence 

 of the capsule surrounding certain organisms, is to pre- 

 pare the cover-slips in the ordinary way, then cover the 

 layer of bacteria upon them with glacial acetic acid, 

 which is instantly poured off (not washed off in water), 

 and the aniline-water gentian-violet solution dropped 

 upon them ; this is allowed to remain three or four 

 minutes, is poured off, and a few drops more are added, 

 and lastly the slip is washed off in water. A very clear, 

 sharply cut picture usually follows this method of pro- 

 cedure. 



STAINING OF SPORES. We have learned that one of 

 the points by which spores may be recognized is their 

 refusal to take up staining substances when applied in 

 the ordinary way. They may, however, be stained by 

 special methods ; of these one that has given very satis- 

 factory results in our hands is as follows : The cover- 

 slip is to be prepared from the material containing the 

 spores in the ordinary way, dried, and fixed. It is then 

 to be held by its edge with the forceps, and its surface 

 covered with Loeffler's alkaline methylene-blue solu- 

 tion. It is then held over the Bunsen flame until the 

 fluid boils ; it is then removed, and after a few seconds 

 is heated again. This is continued for about one min- 

 ute, after which it is washed off in water and dipped 

 five or six times in alcohol containing about 0.2 to 0.3 

 per cent, of hydrochloric acid. This is rinsed off in 

 water and the preparation is now stained for from eight 

 to ten seconds in aniline-water fuchsin solution (Koch- 

 Ehrlich solution), and finally again washed in water. 

 By this method the spores are of a blue color and the 

 body of the cell red. 



