89 



border, a woolly, smoky aerial surface, and was black at contacts. H. 

 Nos. 11, 12, and 17 were otherwise colored. 



Carrot plugs on glass slips (manipulated as above). H. No. 1 gave 

 black border and scant aerial mycelium; H. Nos. 11 and 17 were quite dif- 

 ferent. 



On other carrot plugs, placed in test-tubes but without the glass 

 slips, H. No. 1 gave at 4 days a slowly developing black surface-growth. 

 H. No. 3 grew faster and with more aerial mycelium. At 9 days, H. Nos. 1 

 and 3 were alike. 



Sweet-potato plugs. H. No. 1 at 4 days was densely woolly on the 

 surface; surface of H. No. 3, less woolly. At 9 days H. Nos. 1 and 3 were 

 alike. 



Onion bulbs; radish root. H. No. 1 and H. No. 3 had abundant myce- 

 lium, a pellicle, and conidia. 



Celery, onion stems, green peas, pea-pods, string-beans. H. Nos. 1 

 and 3 had made dense, white, woolly aerial mycelium. 



Rhubarb stems. H. No. 1 made no growth; H. No. 3, poor growth. 



Cranberries. H. Nos. 1 and 3 made no growth. 



Bean broth. H. Nos. 1 and 3 gave a thick pellicle and a scant aerial 

 mycelium. This medium has little differential value, though large white 

 mycelial clumps appeared in H. Nos. 7, 8, and 9, much less in No. 6, and in 

 some cases there was no pellicle. These characters, however, appear too 

 variable to have value. 



Old wheat-straw. Old, dry wheat-straw, cut free of leaves and into 

 lengths of about 12 cm., was placed in test-tubes with a few c.c. of water 

 and autoclaved. Inoculated on these straws, II. No. 1 grew well, largely 

 covering the lower part of the stem (which was in the most humid air) 

 with a black coating of conidia. Each conidiophore usually produced 

 several conidia. On the upper part of the stem, which was in less humid 

 air, conidia were produced much less abundantly and were usually solitary 

 on the conidiophore, while on the portion of the stem very near the cotton 

 plug there was a growth of aerial mycelium. The fungus also grew sparsely 

 over the surface of the water, where it produced conidia. Nineteen other 

 numbers of Helminthosporium were grown on this medium and kept 

 under observation more than three months. Three numbers, 11, 17, 

 and 21, showed distinctive characters, and among the others there were 

 minor differences in conidia production, in amount of aerial mycelium on 

 the upper end of the straw, and in the density of the pellicle. These 

 differences were, however, as great between two cultures known to be 



