308 



PATHOGENIC YEAST-LIKE FUNGI 



it has not yet been tested in a sufficient number of cases for critical 

 evaluation. 



Morphology in Tissues. The cells of Cryptococcus neoformans 

 are usually nearly spherical and this symmetry is not disturbed when 

 the cell buds (Fig. 123). Unlike typical budding of most yeasts, the 

 bud arises as a minute projection from the side of the parent cell and 

 the connection between the mother and daughter cell always remains 

 narrow. The bud secretes a capsule of its own, but frequently both 





Fig. 123. Section through the meninges from a case of infection with Cnjpto- 



coccas neoformans. Note the variation in size of the yeast cells, and the wide 



capsular spaces surrounding them. Drawing by Dr. J. C. McKinley. 



encapsulated cells are surrounded also by a single enveloping capsule. 

 The capsular material is produced in such quantity that frequently 

 in tissue the total diameter of the capsule is as much as three times 

 that of the cell proper. The budding cells, varying greatly in size 

 and surrounded by the clear halos representing the capsules, may 

 appear in considerable numbers and, by displacing host cells, par- 

 ticularly in certain tissues such as the meninges, form pockets in 

 which the abundance of fungi and the absence of host tissue simulate 

 a pure culture of the fungus. The cells vary in their reaction to 

 Gram-staining. 



Morphology in Culture. In culture Cryptococcus neoformans 

 grows as spherical cells varying considerably in size and exhibiting 

 the same peculiarities of budding as described above for the parasitic 

 growth phase. In young cultures the capsule surrounding the cell 

 may not be apparent unless the cells are mixed with dilute India ink 



