66 



STUDY AND IDENTIFICATION OF BACTERIA 



Diplococcus Crassus. This is a Gram-positive, kidney-shaped dip- 

 lococcus, which might be confused with the M. catarrhalis or the Menin- 

 gococcus by ordinary staining methods. It is larger than the Meningo- 

 coccus. 



It is not strongly Gram-positive as one may find examples in the same prepara- 

 tion about which doubt may be entertained. It ferments lactose and saccharose 

 as well as glucose and maltose. 



In throat cultures I have isolated on several occasions a Gram-positive diplococcus 

 which is at times biscuit-shaped, at times irregularly spherical. It possesses two 

 or three metachromatic granules, so that in a Neisser stain for diphtheria the 

 appearance of these granules may be confusing. 



Using Ponder's toluidin blue stain I have observed granule staining in organisms 

 of round or oval morphology which were suggestive of the ascospore staining of 

 yeasts. Staphylococci may show granules with Ponder's stain. 



Gram-negative Cocci. It is important to bear in mind that there 

 are many cocci of varying shapes, which in cultures or in smears from 



FIG. 15. Gonococcus. Film from urethral pus. (Coplin.) 



the throat, nose or faeces are Gram-negative. These are not well classi- 

 fied or described. To distinguish the three important kidney-shaped 

 diplococci, it can be most easily accomplished by cultural methods, 

 using hydrocele agar (ascites or blood agar will answer), ordinary blood- 

 serum and plain agar. The Gonococcus will only grow on the hydro- 

 cele agar; the Meningococcus will grow on this, but likewise grows on 



