166 BACTERIOLOGY. 



V. Bacillus Diphtherise. 



This is found in diphtheretic membrane. It is a non-motile, aero- 

 bic species. On agar it produces a yellowish- white growth, with cre- 

 nated edges. The rods are straight, or curved, and, when stained, 

 often present the appearance of a dumb-bell, owing to the deeper 

 staining of the polar protoplasm. It grows best at 35 degrees Cen- 

 tigrade, and stains well with Loffler's methylene blue. 



The antitoxin of diphtheria is produced by inoculating a horse 

 with a small amount of diphtheria toxin and following this up with 

 an increased dose every six days, until upwards of 1,000 c.c. can 

 be introduced at a time. As a result of this, the serum of the blood 

 becomes immune to the influence of the toxin. A portion of the 

 blood is then removed from the jugular vein of the horse, and, after 

 coagulation, the serum is tested, bottled, and sold in so-called units 

 of strength. A unit of antitoxin has been tersely denned by Mac- 

 Farland as "ten times the least amount of antitoxic serum that 

 will protect a standard (300-gram) guinea pig against ten times the 

 least certainly fatal dose of diphtheria toxin." A child of the writer 

 was supposed to have diphtheria, bacteriological tests made imme- 

 diately proving the suspicion to be well founded. Within twenty- 

 four hours of the first appearance of the diphtheretic membrane, 

 100 units of antitoxin were administered, and in three days the child 

 was considered well. 



VI.. Staphylococcus Pyogenes Aureus. 



This species occurs in suppurations. The cells are spherical in 

 form and occur singly, or in clusters resembling bunches of grapes, 

 called zooglcese. It is a non-motile anaerobic facultative parasite. 

 It produces a yellowish growth on agar, grows at the room tem- 

 perature, liquefies gelatin, and stains well with aqueous solutions. 



VII. Streptococcus Pyogenes. 



Streptococcus pyogenes is found in erysipeloid suppurations. The 

 cells are spherical, and occur in pairs and chains. It is a non-mo- 

 tile facultative anaerobe, growing best at 35 degrees Centigrade, 

 producing a grayish- white line on agar-agar. It stains well with 

 aqueous fuchsin, or gentian-violet. 



