74 

 EXERCISE XI^IV. 



BACTERIUM (BACII^LUS) DIPHTHERIAE. 



§ 126. .Explanatory note. The bacterium of diphtheria 

 is often called the Klebs-IyOeffler bacillus. It is the specific 

 cause of diphtheria in man but it is not, so far as known, the 

 cause of diphtheria in pigeons and poultry. It is found in 

 the throat of people suffering with diphtheria, but it is not 

 found ordinarily elsewhere in the body. Its appearance in 

 the throat lesions is availed of in diagnosing the disease. 

 For this reason it is especially important that its morphology 

 as well as its cultural characters should be carefully deter- 

 mined. Although this organism grows on nearly all of the 

 media commonly used, its development is more rapid and its 

 growth more characteristic on l,oeffler's blood serum. The 

 bacterium of diphtheria seems to be modified in its morphol- 

 ogy in growing on different media more than any of the 

 other pathogenic bacteria. Particular attention should be 

 given to its morphology and staining properties. 



§ 127. General Directions. Examine and describe the 

 cultures made in Exercise XLIII. 



Examine the agar and bullion cultures microscopically in 

 (i) hanging-drop preparations, and (2) stained cover-glass 

 preparations. Stain with alkaline methylene-blue and with 

 carbol fuchsin. Also stain a preparation after Gram's 

 method. 



Inoculate a tube of glycerine agar, one of blood serum, and 

 one of Loeffler's blood serum from the agar culture. 



The blood serum and Loeffler's serum necessary for this 

 exercise will be furnished. 



§ 128. The preparation of blood serum. When a 

 small quantity is sufficient it can be obtained from a dog 

 aseptically. The animal is properly tied on the operating 

 table, etherized, the skin over the carotid or femoral artery 



