DIPLOCOCCUS CEASSUS 553 



colonial appearance or on the basis of laevulose fermentation is most unsatisfactory. 

 We must await further work before a classification can be attempted. 



N. pharyngis sicca. — -According to von Lingelsheim (1906) this organism consists of 

 fine Gram-negative diplococci. On agar it gives rise to an irregularly round, raised, 

 opaque, slightly yellowish colony, up to 3 mm. in diameter, with a dull, dry, deeply 

 furrowed surface, and a crenated edge ; the colony is very firm, often adherent to 

 the medium, difficult to disintegrate, and impossible to emulsify ; it is so coherent 

 that it can be picked up bodily, von Lingelsheim says that it produces acid in glucose, 

 maltose, and Isevulose. but other workers have found that it also ferments sucrose (Elser 

 and Huntoon 1909, Gordon, J. E., 1921). It seems doubtful whether this organism 

 should be regarded as a distinct species. Our own work suggests that it is merely 

 a rough variant of one of the other nasopharyngeal 

 cocci which ferments glucose, maltose, and sucrose. We 

 have observed the formation by cocci giving these sugar 

 reactions of smooth colonies when first isolated from 

 the nose, and the appearance in later cultures of 

 tj^pically rough colonies indistinguishable from those 

 described as being characteristic of A'^. pharyngis sicca. 



N. pharyngis cinerea. — von Lingelsheim (1906) de- 

 scribed this organism as consisting of plump cocci, 

 arranged in pairs or more usually loose heaps. On 

 agar it forms small, round, grey or greyish-white colonies, 

 ' 1-1-5 mm. diameter, with an entire edge; under a low t^,^ ,,« v„,„„^^v^ ^;,„^., ^v, 



magnification their colour is brownish, and they appear op. 



"^ , , „ , 1 1 1 - buriace colony on agar, 24 



coarsely granular, home authors state that the colonies hours 37° C. X 8 showing 



are dry, brittle, and opaque (Netter and Debre 1911). primary rough type of 



It ferments no sugars. This organism closely resembles colonial variant. 



N. catarrhalis and is probably merely a variety of it ; 



it corresponds closely in description to Gordon's N. catarrhalis sub-group III (Gordon, 



J. K, 1921). 



Diplococcus mucosus. — This organism, which was isolated by von Lingelsheim (1906, 

 1908) from the nasopharynx and cerebrospinal fluid, is distinguished by its capsulation, 

 growth on plain agar, growth at room temperature, and formation of mucinous colonies. 

 Microscopically it consists of small diplo- and tetracocci surrounded by true capsules. 

 Colonies are 1-5-4 mm. in diameter, convex, yeUowish-grey, opaque, mucmous, and easily 

 emulsified. Gelatin is not usually liquefied. McFarlan's (1941) and Bray and Cruick- 

 shank's (1943) strains grew on MacConkey's agar, fermented glucose only, and did not 

 liquefy gelatin. Cowan's (1938) two strains grew on MacConkey's agar, produced late 

 acid from lactose, and acid and clot in litmus milk. Most strains seem to be pathogenic 

 for mice. The systematic position of this organism is still in doubt. It may be noted 

 that an organism resembling Diploccus mucosus is not infrequently present in infected 

 wounds and burns. 



Diplococcus crassus. — This organism is not easy to define. It was first described 

 by Jaeger (1895) as a meningococcus, but as it was said to form long chains in culture, 

 to be Gram-positive in the cerebrospinal fluid and in pure cultures, to be able to grow 

 on gelatin at room temperature, and to be highly resistant to drying, it is certain that 

 it was not the meningococcus (Jaeger 1903a). On agar it forms rather small, greyish- 

 white, granular colonies, 1-1-5 mm. in diameter, with an entire edge. Growth occurs 

 at 20° C. Microscopically it consists of plump diplo- and tetracocci, some of which are 

 Gram-positive and some Gram-negative ; it appears in reahty to be a Gram-positive 

 organism that is very easily decolorized. Its sugar reactions differentiate it from all 

 the other members of the group, since in addition to fermenting glucose, maltose, Isevu- 

 lose, and sucrose, it ferments lactose. It is said to be sometimes agglutinated by anti- 



