38 PARASITES BELONGING TO THE GENUS GLOMEEELLA. 



For generation 4, six transfers were made of perithecia from genera- 

 tion 3. These soon developed numerous small acervuli with setse. 

 Few perithecia formed in these cultures. Other cultures made at 

 the same time from ascospores from another series from this host 

 made a growth of quite different appearance, no acervuli and very- 

 few conidia being formed. Few perithecia appeared. A further dis- 

 cussion of the pedigreed cultures will be given later. 



Five transfers of single conidia were made from a plate subculture 

 originally from a single ascospore culture. The growth produced in 

 the five tubes was identical in appearance. A few acervuli developed 

 near the point of inoculation and concentric rings of perithecia 

 extended to the base of the culture. No asci were produced, however, 

 so far as could be found. Plates poured from conidia from one of these 

 tubes developed an abundance of conidia, but no distinct acervuli 

 were formed. Chlamydospores and perithecia were present, but, as 

 in the preceding generation, no asci developed. 



The spores of this form, both ascospores and conidia, were very 

 variable in size. The conidia in cultures ranged from 12 to 33 by 

 4.5 to 7 pi. On the host they ranged from 12 to 21 by 4.5 to 6 /i. 

 Ascospores from the host ranged from 13.5 to 23 by 4.5 to 5.5 fi. 

 Ascospores from cultures varied from 16.5 to 24 by 5 to 6 p. 



Miss Stoneman (89) gives the ascospore measurements of this 

 species as 20 to 28 by 5 to 7 /x, which still further extends their range 

 of variation. Unless the study of a vast number of spores from 

 various localities should establish a constant mean spore measure- 

 ment decidedly different from that found in Glomerella from other 

 hosts, there seems to be no way of distinguishing this plant specifically 

 from it. An ascus and ascospores are shown in Plate II, figures 17 

 and 17a, 



MALUS SYLVESTRIS MILL (APPLE ). 



Glomerella cingulata (Stonem.) S. and v. S. 

 Glomerella rufomaculans (Berk.) S. and v. S. 

 Gloeosporium fructigenum Berk. 



Several attempts were made to develop this fungus from twigs of 

 the 1 -year-old growth taken from trees which had been badly 

 affected with bitter-rot. In the 12 trials made no Gloeosporium 

 was obtained in the cultures. 



The production of the perithecial form from this host has already 

 been described by several writers, both on the host and in pure cul- 

 tures. It is therefore unnecessaiy to give a detailed account of our 

 work on this point. Fertile perithecia of Glomerella are often pro- 

 duced on apples which have been attacked by bitter-rot; and they are 

 also frequently obtained in cultures, though their production can not 

 be depended upon in any particular strain. Here, as in forms from 



252 



