22 BACTERIA ! FORMS AND REPRODUCTION 



shaped bacillus. This is spoken of as polar germination. 

 In Bs. mycoides the protoplasm of the spore grows out 

 through an opening which arises in the side of the spore 

 (equatorial germination), the time taken for complete 

 germination being in many cases about three or four 

 hours at a temperature of 30 C, (Fig. 12). 



i i 



FIG. 12. i. Equatorial germination of spore. 

 2. Polar germination of spore. 



Ex. 12. Staining of Spores. Prepare cover-glass films of 

 "scum" from an old hay decoction (par. i, Chap. I.) and from 

 other old cultures likely to contain bacteria with spores. Fix 

 by passing through flame three times. Wash for two minutes in 

 chloroform to get rid of any drops of fat and other materials. 

 Wash with water and dry with filter paper. Pass through Bunsen 

 flame again. 



Place now in a 5 per cent, solution of chromic acid for twenty 

 to thirty seconds (in some cases ten seconds is enough, in others 

 better results are obtained if left for two to three minutes or 

 longer ; further trials must be made if twenty to thirty seconds 

 give poor results). Wash in water. Dry and fix again. 



Place now in carbol-fuchsin (Ex. 8) and heat for three minutes. 

 Wash with water and dip into 5 per cent, sulphuric acid for five 

 seconds to get rid of the fuchsin from all parts of the bacteria 

 except the spores. Wash again in water and then stain for a 

 minute with LoefHer's methylene blue (Ex. 7). Each spore 

 will be stained red and the rest of the bacillus blue. 



Ex. 13. Apply films to cover-glasses, leave to dry in air with- 

 out heat. When dry, place in hot J per cent, hydrochloric acid 

 for three to four minutes. Wash with water, dry and fix in 

 flame. Then stain with carbol-fuchsin ; wash in acid and counter 

 stain with methylene blue as in above Exercise. 



