64 PARASITES BELONGING TO THE GENUS GLOMERELLA. 



CONIDIA. 



The conidia show exceeding variability in their manner of produc- 

 tion and all their morphological characters. In some cultures they 

 are borne separately on scattered sporophores, suggesting a very dif- 

 fuse hyphomycete. All intergradations between this form and forms 

 having very large, compact, and distinct acervuli occur. In one strain 

 derived from the gooseberry, certain cultures produced an aerial 

 growth and conidiophores more or less erect and clustered, suggesting 

 in macroscopic appearance a Verticilhum. Pure cultures from these 

 conidia, however, produced the usual form with acervuli, which was 

 followed by the development of perithecia and ascospores. In size, 

 shape, and color the conidia are also very variable. They have been 

 found to range from 10 to 42 by 3 to 9 p. from the same host. They 

 are rarely or never distinctly curved. When scattered on a slide they 

 usually appear colorless, but vary from a very pale-cream to a bright- 

 salmon color in masses. Occasionally a few dark-colored conidia have 

 been found. 



SETuE. 



Setae are frequently entirely wanting in some cultures while abun- 

 dant in others from the same host. Some acervuli from one single- 

 spore culture may show many setse, others few, and still others none. 

 The setse also vary greatly in size, length, and septation. In two 

 forms, those from cotton and Theobroma, they have been found bear- 

 ing conidia. 



APPRESSORIA, OR CHLAMYDOSPORES. 



The appressoria, or chlamydospores, are also exceedingly variable in 

 size and shape. As has been pointed out by Hasselbring (45) and 

 others, their occurrence appears to bear some relation to lack of 

 available nutriment and to contact with some hard surface. 



In water drop cultures on glass slides they usually develop either 

 from conidia or ascospores in 24 to 48 hours. (See figs. 2 and 3.) 



A germinating chlamydospore is shown in figure 4. 



YEAST AND OTHER FORMS. 



Viala and Pacottet (92) have reported the occurrence of yeast forms 

 of Gloeosporium. Yeast forms have never occurred in any of the 

 writers' pure cultures. They have occasionally been found, but only 

 in cultures made directly from fruit, in which cases they were evidently 

 contaminations. The same authors also report the production of 

 spermagonia and pycnidia in Colletotrichum lindemuthianum. No 

 fructifications of this kind have ever been found by the writers in pure 

 cultures of Glomerella. The writers have never seen the endospores 

 described by Sheldon (79) and confirmed by Taubenhaus (91). 



252 



