338 An Introduction to Medical Mycology 



(g) Animal inoculation.— Mice and rats are the most susceptible and 

 rabbits and guinea-pigs less so (Benham). The infective material, diluted 

 in saline, should be injected intraperitoneally. The animal usually dies 

 within two to four weeks. 



(h) Differential diagnosis.— In M. albicans mycelium develops, par- 

 ticularly on corn meal agar. The cell of B. dermatitidis is larger and lacks 

 the thick mucinoid envelope of T. histolytica. The cells of C. immitis con- 

 tain endospores. Other, nonpathogenic cryptococci are not pathogenic to 

 mice. 



BIBLIOGRAPHY 



Benham, R., in Gay, F. P., et ah: Agents of Disease and Host Resistance (Springfield, 111.: 



Charles C Thomas, Publisher, 1935), p. 1115. 

 Weidman, F. D., and Freeman, W.: India ink in microscopic study of yeast cells, J. A. M. A. 



83:1163, 1924. 



27. RHINOSPCRIDIUM SEEBERI 



This is the cause of rhinosporidiosis, a rare fungous disease with a predi- 

 lection for the anterior nares. The fungus was first described by Ash worth 

 in 1923. 



(a) Microscopic features.— The material for examination may consist of 

 freshly prepared slides from nasal secretion or tissue or stained slides from 

 a biopsy section. The micro-organism is large (up to 250 microns in di- 

 ameter), thick-walled and spherical. There are many endospores which 

 are eventually discharged. In a histologic slide the fungus is in the cutis. 



(b) Cultural characteristics.— This fungus is reputed not to grow on 

 ordinary laboratory mediums. We have had no experience. 



(c) Animal inoculation.— No laboratory animal is susceptible. 



(d) Differential diagnosis.— When the site of a polypoid growth of the 

 nose is the source, R. seeberi should be suspected. There may be a super- 

 ficial resemblance to C. immitis, but the large size of R. seeberi should alone 

 be sufficient to distinguish the two fungi. 



bibliography 



Vshworth, J. H.: On Rhinosporidium seeberi (Wernicke, .1903), with special reference to its 

 sporulation and affinities, Tr. Roy. Soc. Edinburgh 53:301, 1923. 



