568 APPLICATION OF METHODS OF BACTERIOLOGY 



duration of the disease was always very much shortened 

 and all recovered. 



Lazaretti 1 reports 23 cases of human infection with bac- 

 terium anthracis in which Sclavo's immune serum was 

 employed with recovery in each case. Another patient, 

 suffering from chronic alcoholism and malaria, did not 

 recover. 



Experiments. Prepare three cultures of bacterium an- 

 thracis one upon gelatin, one upon agar-agar, and one upon 

 potato. Allow the gelatin culture to remain at the ordinary 

 temperature of the room, place the agar-agar culture in the 

 incubator, and the potato culture at a temperature not 

 above 18 to 20 C. Prepare cover-slips from each from 

 day to day. What differences are observed? 



Prepare two potato cultures of bacterium anthracis. 

 Place one in the incubator and maintain the other at a 

 temperature of from 18 to 20 C. Examine them each day. 

 Do they develop in the same way? 



From a fresh culture of bacterium anthracis, in which 

 spore-formation is not yet begun (which is the surest source 

 from which to obtain non-spore-bearing anthrax bacteria?), 

 prepare a hanging-drop preparation; also a cover-slip 

 preparation in the usual way and stain it with a strong 

 gentian- violet solution; and another cover-slip preparation 

 which is to be drawn through a flame twelve to fifteen times, 

 stained with aniline gentian-violet, washed in iodine solu- 

 tion and then in water. Examine these microscopically. 

 Do they all present the same appearance? To what are 

 the differences due? 



1 Deutsche Vierteljahrsschrift f. offentliche Gesundheitspflcge, 1903, 

 Bd. xxxv, Supplement, p. 253. 



