Feb. i,i 9 2i Variations in Colletotrichum gloeosporioides 733 



the rest of the growth in that plate. These mutations usually appeared 

 as wedge-shaped or fanlike areas with the point of origin usually at the 

 center of the culture. Sometimes they occurred more toward the periph- 

 ery of the culture. (PI. 86, A, B.) 



Mutations occurred in the following strains: 943, 297, 615, 495, 940, 

 510, 561, 536, 527, and 990. These mutations have remained true to 

 the characteristics manifested by the first culture. Figure 2 will serve 

 to illustrate the manner in which the mutations originated. Since these 

 strains were not progenies from a single spore, it was thought that there 

 might be a possibility of having a mixture of strains. 



There are several types of these variations. One type had a white, 

 fluffy mycelium. A second type, where the mycelium was confined in 

 the medium, had abundant spore production on the surface. A third 

 type had varying shades of gray mycelium bearing spores. At first these 

 peculiarities in growth were regarded as modifications due to some envi- 

 ronmental factor. However, after these variations were transferred to 

 other culture tubes and the resulting cultures always exhibited the same 

 characteristics, they then were considered as mutations. Therefore, 

 single-spored cultures were made from one of the strains. 



SINGLE-SPORED ISOLATIONS 



On November 14, 191 7, single spores were isolated from culture 990. 

 The spores were taken from oatmeal agar, and a suspension was made in 

 sterilized distilled water. A platinum loop was used to transfer a drop of 

 the suspension to a cover glass. Each cover glass was examined with 

 the microscope, and when a drop contained only one spore the cover 

 glass was dropped into a test tube containing potato agar. Three cul- 

 tures were thus obtained and were designated as 990A, 990B, and 990C. 

 After the spores had germinated and had produced a mycelium, transfers 

 were made to the five media used in culturing the various strains. The 

 growth characteristics of cultures 990A, 990B, and 990C were identical 

 with those of the original culture 990. 



On November 26, 1917, transfers were made from culture 990C to 

 potato agar plates. The resulting growth was composed of black and 

 white mycelia, with abundant production of spores in the center of the 

 culture (PI. 86, C). On December 12, 191 7, transfers were made from 

 the white and black mycelia to potato agar plates from the cultures 

 made November 26, 191 7. The plates made from the black mycelium 

 became black with some white mycelium. The plates made from the 

 white mycelium were white, but only slight traces of black growth could 

 be detected. All cultures produced abundant spores. 



On January 9, 191 8, transfers were again made from the two kinds 

 of cultures obtained in transfers of December 12, 191 7, with results simi- 

 lar to the transfers of December 12, with the exception that there was 



