294 MICROBIOLOGY 



erally believed that diphtheria in fowls is not caused by this 

 organism. Klein 3 studied the reaction produced in milch 

 cows inoculated with the bacteria of human diphtheria. The 

 inoculated cows developed a peculiar eruption on the teats 

 and udder. Abbott 4 failed to confirm the results of Klein. 

 Dean and Todd 5 more recently traced two cases of diphtheria 

 to the consumption of milk from cows having a peculiar erup- 

 tive disease of the teats and udder. 



Bacterium diphtheriae was first observed by Klebs in 

 1883 and the following year it was isolated and studied in 

 pure culture by Loeffler. 7 It is often called the Klebs-Loeffler 

 bacillus in honor of its discoverers. 



Morphology. The diameter of the Bact. diphtheriae 

 varies from 0.3 to 0.8 /A, and the length from 1 to 6 /*. They 

 occur singly and in pairs, and very infrequently in chains 

 of three or four. The rods are straight or slightly curved, 

 and usually are not uniformly cylindrical throughout their 

 entire length, but are swollen in the middle portion. Their 

 average length in pure cultures from different sources fre- 

 quently varies greatly, and even from the same culture indi- 

 vidual organisms differ much in their size and shape. They 

 do not produce spores, but they have highly refractile bodies 

 or granules. 



Staining. The Klebs-Loeffler bacteria stain readily with 

 ordinary aniline dyes, and retain fairly well their color after 

 staining by Gram's method. With Loeffler 's alkaline methy- 

 lene blue, and to a less extent with Roux's and dilute Ziehl's 

 solutions, they stain in an irregular and characteristic way, 

 especially when grown on blood serum. They do not stain 

 uniformly. In many cultures round or oval bodies, situated 

 at the ends or in the central portions, stain much more in- 



3 Klein. 19th annual report of the local Gov. Board, Supplemen- 

 tal report of the medical officer, 1889-90. 



4 Abbott. Jour, of Path, and Bact, Vol. II (1894) p. 35. 



5 Dean and Todd. The Jour, of Hygiene, Vol. II (1902) p. 194. 

 Klebs. Kongress f. neue Medicine, 1883. 



7 Loeffler. Mitt. a. d. Kaiserl. Gesundheitsamt, Bd. 11 (1884) 

 p. 421. 



