GRAM NEGATIVE COCCI. 47 



culture is to inject the sputum into the marginal ear vein of a rabbit or 

 subcutaneously into a mouse. Death results from septicaemia in 

 about two days and the blood teems with pneumococci. Usually the 

 pneumococcus quickly loses its virulence, and also dies out in a few 

 days unless transferred to fresh media. The best medium for it 

 preservation is rabbit's blood agar; this also maintains the virulence. 

 On this medium the colonies are larger than on agar and they present 

 a greenish appearance with a hemolytic zone. It is a well-known fact 

 that the pneumococcus is a frequent inhabitant of the nasal and buccal 

 cavities. The explanation of infection is either on the ground of 

 lowered resistance of the patient or enhanced virulence of the organ- 

 ism. Oscar Richardson has reported an organism in cases of lobar 

 pneumonia, cerebrospinal meningitis, mastoid disease, etc., bearing 

 resemblance to both pneumococci and streptococci the Streptococcus 

 capsulatus. It differs from the pneumococcus in that the colonies on 

 blood-serum are viscid and like irregular flecks of mucus. The 

 characteristic culture is a glucose agar stab. (Reaction must not 

 exceed + .5.) From the line of puncture there are flail like projections 

 extending outward from one-fifth to one-fourth of an inch. The 

 capsule persists on culture media. This organism resembles the 

 Streptococcus of Bonome of the French. 



Diplococcus Crassus. This is a Gram positive, biscuit-shaped 

 diplococcus, which might be confused with the M. catarrhalis or the 

 meningococcus by ordinary staining methods. 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. 



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 

 the throat, nose or feces are Gram negative. These are not well 

 classified or described. To distinguish the three important biscuit- 

 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 hydrocele agar; the meningococcus will grow on this, but 



