VAEIABILITY OF GLOMEKELLA. 



65 



Fig. 2.— Germinating conidia of Glomerella cingu- 

 lata from a culture from pear, showing the for- 

 mation of chlamydospores after 24 hours in drop 

 cultures of sterile water. 



PERITHECIA. 



Perithecia have been found to vary in abundance, size, shape, 

 arrangement, and location with reference to the surface of the me- 

 dium. They are generally glo- 

 bose or subglobose, though some- 

 times elongated or pear shaped. 

 The beak when present is usually 

 very short, though commonly 

 the perithecia are merely papil- 

 late. In rare cases, however, 

 they have been found with dis- 

 tinct elongated beaks similar to 

 those illustrated by Stoneman 

 (89). On the host plant they 

 have always been found embedded 



in the tiss ues. In artificial cultures they are usually embedded but 

 occasionally form erumpent, superficial masses. Sometimes they 



are evenly scattered 

 and entirely separate, 

 as shown in Plate 

 XV; at other times 

 they are aggregated 

 and seated upon a 

 more or less distinct 

 stromatic base. Oc- 

 casionally they are 

 almost sterile or are 

 represented by simple 

 black, solid, sclero- 

 toid bodies. 



Fig. 3.— Germinating ascospores of Glomerella cingulata from cultures 

 from gooseberry, showing formation of chlamydospores after 55 

 hours in drop cultures of sterile water. Ascospores usually produce 

 longer germ tubes than conidia. 



ASCI. 



The asci are also 

 extremely variable in size and shape, as will be observed by a com- 

 parison of Plates I, II, and III and the measurements of speci- 

 mens from the same and 

 different hosts, as recorded 

 in Table III. The apex 

 of the ascus shows a 

 peculiar structure which 

 apparently has some rela- 

 tion to the expulsion of 

 the spores. This feature 

 46023°— Bui. 252—13 5 



Fig. 4.— A germinating chlamydospore, or appressorium, of 

 Glomerella cingulata from a culture from gooseberry, showing 

 the development of the germ tube after 24 hours in corn- 

 meal agar. 



has been discussed by Koorders (54). 



