986 THE HIGHER BACTERIA, MOLDS AND FUNGI 



and pairs united in a figure eight can usually be found. They stand 

 out more definitely if the pus is cleared by mixing with a 10 per cent 

 potassium hydrate solution. They stain irregularly. As a rule 

 with the stronger aniline dyes they are overstained so that the 

 details are obscured. With hemotoxylin eosine the capsule usually 

 remains unstained and the body takes a pale stain with deep blue 

 granules but in some cells the capsule may stain deeply. Thionine, 

 polychrome methylene blue, and Wright's blood stain have been 

 recommended. In tissue sections stained with hemotoxylin and 

 eosin, or better with thionine, or methylene blue the clean cut, 

 circular parasites are easily recognized, lying, as a rule, within 

 multinuclear giant cells. 



Isolation. The isolation of the organism is rendered difficult by the 

 frequent presence in the lesions of bacteria which develop more rapidly 

 than the fungus. Gilchrist and Zinsser encountered Gram-positive cocci, 

 others diphtheroid bacilli. No special methods for facilitating isolation have 

 been devised but success will often attend painstaking and repeated plating 

 of the cultures in high dilution. The most favorable medium is glucose 

 agar and the organisms develop well at room or at incubator temperature. 



Cultural Characteristics. On agar or glucose agar the colonies appear 

 after two to four days as minute glistening white hemispherical spots which 

 are not unlike colonies of staphylococcus albus. In older cultures the appear- 

 ance of different strains shows marked variations, some remaining smooth 

 and pasty, others changing to a tough wrinkled membrane firmly adherent 

 to the agar, and still others becoming covered with white aerial hyphae. All 

 become brown with age. In agar stab cultures the organisms show their 

 preference for a well oxygenated environment by growing but slightly along 

 the course of the stab and by heaping up a thick creamy layer on the 

 surface of the medium. Most strains fail to liquefy gelatine. In broth 

 cultures the medium remains clear, the organisms growing as a stringy 

 sediment, as a pellicle, or as tufted masses in the depth of the medium. On 

 blood serum, potato and bread growth is easily obtained. Some strains 

 ferment carbohydrates but most do not. 



Morphology. In freshly isolated cultures the growth consists 

 of large round cells with blastospores like those seen in the tissues. 

 Capsules are often formed. Most strains sooner or later develop 

 coarse, irregular, branching mycelial filaments. These are divided 

 by septa and produce chains of arthrospores and terminal or lateral 

 conidia. Hamburger 1 '- in a careful culture study of four strains 



12 Hamburger, Jour. Inf. Dis., 1907, IV, 201. 



