DIPHTHERIA. 149 



Solution No. 1. 



Alcohol (96 per cent.), 20 parts ; 



Methylene-blue, 1 part ; 



Distilled water, 950 parts ; 



Glacial acetic acid, 50 parts ; 



Solution No. 2. 



Bismarck -brown, 1 part ; 



Hot distilled water, 500 parts. 



Put a cover-glass prepared in the usual way for two or three 

 seconds into No. 1 ; then pass into No. 2 and let it remain 

 there for three to five seconds ; wash, air-dry, mount in 

 balsam. The body of the bacteria will be stained brown, 

 and the usually darkly stained granules with the Loeffler 

 method will be stained blue. If the bacilli under examina- 

 tion are true diphtheria bacilli, the majority of them will show 

 the blue granule. If the bacilli are pseudodiphtheritic bacilli, 

 scarcely any or few will show a blue stain in their interior. 



Biologic Characters. The Bacillus diphtheria? is aerobic, 

 but can grow in the absence of oxygen, and is therefore a 

 facultative anaerobic ; it is non-motile, has no flagella, does not 

 form spores, and does not liquefy gelatin. 



Its thermal death-point is 58 C. It grows at ordinary 

 room temperature, but slowly. Its maximum of growth is 

 between 37 and 38 C. It "is easily killed by disinfectants. 

 To destroy the bacilli in the throats of infected persons, es- 

 pecially in convalescents, where they have a tendency to per- 

 sist sometimes for weeks, pure H 2 O 2 solution, U. S. P., applied 

 directly with a swab, has proved most efficacious. Exposure 

 to direct sunlight destroys the bacilli in a few days. In 

 albuminous fluid and in the dark it may live, even when 

 dried, for months. It grows on all artificial culture-media, 

 but best in blood-serum prepared after the formula of Loeffler, 

 a modification of which, employed in many municipal labora- 

 tories, is as follows : 



