60 PARASITES BELONGING TO THE GENUS GLOMERELLA. 



Of generation 16, tubes b and c scarcely differed from 15. Acervuli 

 and perithecia were present in both. They are shown in Plate IX. 

 Seven subcultures from tube 16 & showed rather regular intergrada- 

 tions from tube 1, which contained perithecia chiefly, to tube 7, which 

 contained chiefly acervuli. These subcultures are shown in Plate X. 



Tubes b and c of generation 17 were strikingly and remarkably 

 different. Tube b produced perithecia in abundance, covering the 

 surface of the medium as in most ascospore generations. A very 

 few small acervuli were present. Tube c showed an abundance of 

 large acervuli and a very few scattered perithecia. These "two 

 cultures are shown in Plate IX together with their parent cultures 

 16 b and 16 c. 



Of 4 subcultures of conidia, numbered 17 d, e,f, and g, from cul- 

 ture 16 b, three showed perithecia predominating like 17 b, and one 

 had acervuli predominating as in the original 16 b. (See PL XII.) 

 Eight more subcultures made from tube 16 & gave four with peri- 

 thecia like tube 17 b and four of an intermediate character, acer- 

 vuli and perithecia both being present. Six other subcultures from 

 tube 16 & resembled the parent culture. None of them showed a 

 continuous layer of perithecia as in tube 17 b. Nine subcultures 

 made from conidia from tube 16 c were all very similar in appearance 

 throughout their growth. Acervuli were first produced as in the 

 parent tube, but an abundance of perithecia later appeared. They 

 were aggregated in masses in marked contrast to those in cultures 

 from tube 16 b. Seven of these tubes are shown in Plate XIII. 

 Out of 8 transfers from culture 17 b, which, as mentioned above, 

 produced perithecia covering almost the entire surface of the medium, 

 7 were almost identical in appearance, showing a great predominance 

 of acervuli and few perithecia, while only one resembled the parent 

 culture. Tube 17 b with 6 of these subcultures is shown in Plate XI. 



Tubes b and c of generation 18 grown from tubes 17 b and c, 

 respectively, were very different in appearance. Acervuli predomi- 

 nated in culture b and perithecia in culture c, just the opposite of 

 the parent cultures. 



Tubes b and c of generation 19 were about like the ordinary conidial 

 cultures. Acervuli and perithecia were both present, but acervuli 

 predominated. Tube 19 b is shown in Plate XII. 



Generation 20 b, from tube 19 b, produced both conidia and peri- 

 thecia, but the latter were more abundant and covered a broad area 

 on both sides of the culture, as illustrated in Plate XII. 



Generations 21, 22, and 23 were all very much like the ordinary 

 conidial cultures in which acervuli predominated and were most 

 conspicuous, although some perithecia were always produced. 



These variations might perhaps be regarded as renewed expression 

 of latent hereditary characters or as mutations. If mutations, we 



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