XI, B, 6 Wade: Cultivation of a Pathogenic Fungus 277 



obtained, it is nonfructifying, is septate in a minority of fila- 

 ments, and the aerial hyphse separate into short cylindrical 

 cells which may later become oval, suggesting the yeastlike 

 fungi. It grows luxuriantly on most laboratory media, and all 

 cultures develop a strong "yeasty" odor. 



Under conditions of animal-tissue parasitism the fungus is 

 extremely modified, appearing primarily as solid, usually round 

 bodies of nuclear material, most of which are free in tissue spaces. 

 These parasites are often identified with difficulty, and in 

 many preparations may be overlooked. They usually multiply 

 by a simple fission to form two bodies, though in some cases, 

 having attained maximum size, a parasite will undergo irregular 

 multiple fission of the nuclear portion to produce botryoid groups 

 of small bodies of different sizes which are ultimately liberated 

 by dissolution of the protoplasm. 



In different conditions of artificial cultivation the basic tissue 

 forms may undergo various changes. In cultures containing free 

 blood or tissue elements, that is, in what may be considered 

 semiparasitic environment, they continue to multiply as parasites, 

 and on no ordinary medium is the saprophytic habit of groM^h 

 recovered. In these cultures, however, often after developing 

 a protoplasm, they undergo modification to the extent that they 

 differentiate within themselves numbers of a peculiar, very 

 small, hyaline spore-granule, this process being inaugurated in 

 the nuclear portion which later loses its identity. Under favor- 

 able conditions some of these spores enlarge, become deeply 

 staining, and repeat the cycle. 



This type of endosporulation is, so far as I have been able to 

 learn, without precedent. The spore-granules are different from 

 bacterial spores in size, regularity, and the capability of with- 

 standing unfavorable conditions except, perhaps, drying. Fur- 

 thermore, but a small proportion of them has proved viable 

 even under the most favorable circumstances. They are still 

 more unlike any of the many types of spores familiar to my- 

 cologists. Hyaline granules seen in fungi — probably of the 

 nature of ordinary lipoid and other protoplasmic granules (as 

 in figs. 44 to 46) — have often been called endospores, though 

 their germination has not been observed. In the described 

 fungus the spore-granules are produced in an entirely different 

 manner and have developed only under conditions of semi- 

 parasitism. 



The large gelatinous bodies which develop in some cultures 

 also seem to represent a condition of semiparasitism and are 

 intermediate between the tissue forms and the free-growing 



