1916] PARASITIC KHIZOCTONIAS IN AMERICA 365 



As a rule the fungus isolated from carnation plants, when grown 

 on green-bean agar, produced a rapid-growing mycelium, which was 

 practically all aerial, loose, and tufted. The most characteristic fea- 

 ture was the production of concentric zones, tho this was not invaria- 

 ble. Of the many hundred cultures made during the past three years 

 from diseased carnation plants on green-bean agar, 90 percent have 

 shown this zonation. This characteristic was influenced by neither 

 light nor temperature. A typical growth on this medium is shown in 

 Fig. 20, "Carnation R.H." A few of the carnation strains grown 

 on the same medium and showing the same type of mycelium produced 

 very indistinct zonation or none, as shown in Fig. 20, "Carnation 

 R.F." Zonation persisted to some extent when the carnation strains 

 were grown on other media than green-bean agar, but it was not so 

 characteristic. 



The two strains from potato did not grow so rapidly nor quite 

 so luxuriantly on green-bean agar as did the carnation strains, but 

 they produced the same even, tufted, zonate growth. Here the zones 

 were closer together. (See Fig. 20, "Potato R. Sol.") 



The growth of the strain from corn on green-bean agar was similar 

 to that of "Potato R. Sol." 



The growth on green-bean agar of the strains from eggplant, let- 

 tuce, Chenopodium, and thistle was different from any of the other 

 forms in that the mycelium grew along the surface, running out ra- 

 dially in strands, which became larger and more tufted at the edge. 

 (See Fig. 21, "Eggplant I. ") 



The strains isolated from alternanthera, coleus, salvia, and poin- 

 settia, when grown on green-bean agar, showed the same even, fluffy 

 to tufted growth. This was also characteristic of the strains from 

 cauliflower, cotton, and sugar cane. Zonation in these strains was 

 varied. (See Fig. 21.) 



The strain from onion when grown on this agar differed radi- 

 cally from the others. The mycelium was bright colored, finer, and 

 almost all submerged. (See Fig. 20.) 



The other strains studied on green-bean agar cannot be put in 

 definite groups, as they shade into one another. However, the growth 

 of the mycelium was somewhat similar in each case ; practically the 

 only difference noted was in the extent of the zonation. 



On corn-meal agar the growth of the strains was similar to a large 

 extent; the only great difference noted was in rapidity of growth. 

 Zonation was very rare on this medium. 



The growth of the strains on oat agar was somewhat variable; 

 zonation was sometimes present and sometimes absent. 



The most characteristic feature of the growth of the majority of 

 the strains on potato agar was the turning brown of both the myce- 

 lium and the medium. This same characteristic, but to a less degree, 



