Feb. 1,1921 Variations in Colletotrichum gloeosporioid.es 735 



practically no black mycelium in the white cultures and but very little 

 white growth in the dark cultures. 



Another set of transfers was made on January 24, 191 8, from the cul- 

 tures made January 9, with the result that the white cultures were pure 

 white but the black cultures still produced white hyphae. All plates 

 produced an abundance of spores. 



Since the spores are asexual, I wished to determine if they would act 

 like parts of the mycelium when transferred. On January 29, 191 8, trans- 

 fers were made from the spores produced by the white mycelium, and 

 the resulting cultures were pure white, producing many spores. Also 

 spores were transferred from the black and white plates, and the resulting 

 cultures were black with some white hyphae, each culture producing many 

 spores. 



The foregoing experiment seems to point to the fact that asexual spores 

 of Colletotrichum gloeosporioides act like mycelium when transferred. 



The various types obtained by the mutations (fig. 2) are similar to the 

 strains I had in culture. Therefore, one might be led to conclude from 

 the foregoing data that Colletotrichum gloeosporioides is constantly giving 

 off new types under natural conditions, as well as in artificial cultures. 



SUMMARY 



(1) Colletotrichum gloeosporioides is a polymorphic species made up of 

 a number of strains. 



(2) The various strains when grown on artificial media give distinct 

 cultural characteristics. 



(3) Each strain is affected by its environment. The growth charac- 

 teristics as well as the spore size are varied by the medium on which 

 the strain is grown. 



(4) This induced variation may be more or less permanent. 



(5) There occur mutations in culture which iesemble the strains iso- 

 lated from the natural environment. 



LITERATURE CITED 



(1) Clausen, Roy E. 



1912. A NEW FUNGUS CONCERNED IN WITHER TIP OF VARIETIES OF CITRUS 

 medica. In Phytopathology, v. 2, no. 6, p. 217-235, 1 fig., pi. 21-22. 

 Index to literature, p. 233-234. 



(2) Edgerton, Claude Wilbur. 



1908. THE PHYSIOLOGY AND DEVELOPMENT OF SOME ANTHRACNOSES. In Bot. 



Gaz., v. 45, no. 6, p. 367-408, 17 fig., pi. 21. Literature cited, p. 405- 

 407. 



(3) Essig, E. O. 



191 1. WITHER-TIP OF CITRUS TREES (COLLETOTRICHUM GLOEOSPOROIDES Penzig). 



In Pomona Col. Jour. Econ. Bot., v. 1, no. 1, p. 25-56, fig. 14-21. 



(4) Fawcett, Howard S. 



1915. CITRUS DISEASES OF FLORIDA AND CUBA COMPARED WITH THOSE OF CALI- 

 FORNIA. In Cal. Agr. Exp. Sa. Bui. 262, p. 149-211, 24 fig. 



