ENDOMYCETALES 147 



stag-e of the young- ascus. The collection of asci into more or less definite 

 fructifications or ascocarps within the host tissue has been attempted in the 

 end member (Taphrinaceae) where, in some species the clavate asci form a 

 palisade layer under the epidermis of the host. 



The other line has early reduced the number of ascospores to a small, 

 definite number, 8, 4, 2, or 1 and, perhaps owing to their habitats, have 

 gradually diminished the amount of mycelium until in the Saccharomycetaceae, 

 true mycelium has disappeared. For further discussion of this line, especially 

 the steps in the gradual disappearance of sexuality, see Chapters XI and XII. 



Coccidioideaceae.- — This family has four genera causing more or less 

 similar lesions in man and in experimental animals, with no saprophytic 

 species so far recorded. Three of the genera are monotypic, from widely 

 separated and rather restricted localities. Coccidioides is mostly restricted 

 to California, Uruguay, and Argentina. Paracoccidioides to Brazil, while Rhino- 

 sporidium has been reported from Argentina, India, and the Mississippi Valley. 

 Histoplasma is known in the ^Mississippi Valley and in Panama. 



The large indefinite number of ascospores (Fig. 23, 19) suggests condi- 

 tions found in the Ascoideaceae, but no conidial stage is knoAvn. Along with 

 increasing specialization for strict parasitism in this family, sexuality has ap- 

 parently disappeared without a trace.* The mycelium is septate and multinu- 

 cleate as in the preceding family. In the host, however, it tends to less and 

 less development until occasionally^ in Coccidioi<les it may be absent, and the 

 ascospore grows in situ to an ascus without any cell division. In Rhinosporidium, 

 this may be the normal condition. A similar disappearance of mycelium is 

 found in the Eremascaceae — Saccharomycetaceae line. In Histoplasma, large 

 functionless tubercles are formed on the walls of the ascus, while in Paracoc- 

 cidioides, the ascospores migrate into the tubercles and are discharged by the 

 rupture of the wall, suggesting partial sporangia of the Mucoraceae. 



COCCIDIOIDES 



Coccidioides Stiles in Rixford and Gilchrist, Johns Hopkins Hosp. Rept. 

 1: 209-268, 1896. 



Posadasia Canton in Posadas, Psorospermiosis infectante generalisada, 

 Buenos Aires, 1898. 



Pseudococcidioides Fonseca in Mazza & Parodi, Bol. Inst. Clin. Quirurg, 

 Univ. Buenos Aires 4: 495-502, Figs. 13-19, 1928. 



The type species is Coccidioides immitis Stiles. 



In tissue, mycelium very rare, mostly large, thick-walled cells Avhich be- 

 come asci and are filled with a large, indefinite number of ellipsoid spores. 

 In cultures, asci rare, mycelium abundant, sometimes approaching raquet 

 mycelium as in Trichophyton, forming arthrospores and chlamydospores. 

 Mycelium septate but each cell multinucleate; witliout sprouting forms on 

 an}' medium so far observed. 



*As this goes to press, Ciferri & Redaelli report isogamous conjugation in a freslily 

 isolated culture of Coccidioides- iwiiiitis, althougli they state apoganiy is the rule. 



