Feb. i, 1921 



Variations in Colletotrichum gloeosporioides 



729 



has its mode at 15 lx, 912 has its mode at 17 lx, and strain 901, which has 

 the largest spores of all the strains, has its mode at 20 /x. 



There was also a certain range of variability in spore width. The 

 variability was not as great as in length. The widths ranged from 3 to 

 8.5 n; in most of the strains the mode was about 4 or 5 /x. In strain 901 

 the variability was from 5 to 8.5 /x with the mode at 6.5 /x. 



In Table IV are given the calculated mean, standard deviation, and 

 probable error of each, for the spore length and width of eight different 

 strains. The measurements were made from spores taken from the 

 green bean plug medium. 



Table IV. 



-Table of calculated spore measurements for certain strains of Colletotri- 

 chum gloeosporioides 



Strain No. 



Mean length of 

 spore in microns. 



Mean width of 

 spore in microns. 



295 

 296 

 298 

 429 

 5°7 

 651 

 901 

 912 



11. 54±o. 065 



12. oi± . 115 

 14- 79± 

 14- 73 ± 

 14. i6± 

 17. 23± 

 20. 34± 



5. 52 ±0.057 



094 

 °95 

 079 

 no 

 x 37 



16. 99 ± .097 



4- 2 ± 

 4. 68 ± 



3. 26± 



4. 91 ± 



4. 52 ± 

 6. 4 5± 



4-7 ± 



065 

 014 

 077 

 048 



°35 

 132 

 no 



0. 85 ±0. 041 



• 97± -046 

 . 2I± . 010 



i-i5± -OS5 



• 7 J ± -°34 

 . 52± .025 



1. 96 ± .093 

 1. 63 ± .078 



This table shows that strains grown on the same medium under like 

 conditions vary greatly in respect to their spore sizes. We can, there- 

 fore, safely conclude that there exist individual differences in the various 

 strains in regard to certain morphological characters. 



VARIATIONS IN THE DIFFERENT STRAINS INDUCED BY THE MEDIUM 



The difference in growth characteristics occurring in the same strain 

 when transferred to the various media was very noticeable. The 

 various strains were grown on the five different media for a period of 

 one year. Transfers were then made from cultures growing on the vari- 

 ous media to different plates poured with the same medium. The plates 

 were kept at room temperature, and their growth characteristics were 

 noted. It was soon observed that some strains had been more affected 

 than others by their previous environment. While some of the variations 

 were slight, still it was impossible to account for this variation other than 

 as the effect of the medium. 



On October 25, 1917, 20 cc. of potato agar were poured in sterilized 

 Petri dishes and allowed to harden. Transfers were then made from the 

 various strains as follows : 



