181 



extensive test of its utility against the cereal smuts is now in progress. 

 Para - toluene - sodium - sulphochloramide is a chemical of the formula 

 (p)CH 3 C 6 H 4 SO(NCl)ONa. My supply was secured from the Abbott Lab- 

 oratories in Chicago, where it is manufactured. 



Preparation of potato plugs. Instead of the ordinary potato plug it 

 was found useful to place a glass slip in a test-tube as in Fig. 2, p. 94, then to 

 crowd into the tube a potato slice, bringing it into contact with the glass 

 slip, and, at its angles, with the walls of the test-tube. This gave, in 

 addition to the usual surface for observation, the places where the potato 

 made contact with the glass slip and with the walls of the test-tube. 



A device for the study of humidity. To study the effect of changes of 

 humidity on conidiophores and conidia, test-tubes were fitted with glass 

 slips, and sterile wheat shoots laid across them (Fig. 2, p. 94). The region 

 1 is of about 90% relative humidity; that of region 2 is below 90%. Com- 

 bustion boats full of agar were used (Fig. 2) to secure high humidity 

 for the whole culture. 



LIST OF HELMINTHOSPORIUMS USED FOR 

 PURPOSES OF COMPARISON 



H. No. 1. Isolated by F. L. Stevens May 18, 1918, from wheat dis- 

 eased with foot-rot, from Madison Co., 111. 



H. No. 2. H. ravenelii, isolated by F. L. Stevens Jan. 17, 1920, from 

 specimen received from A. B. Seymour, collected at Lake Charles, La., 

 Oct., 1919, by E. E. Barnes. This specimen was thoroughly typical, 

 and no doubt as to the determination can be entertained. 



H. No. 3., labeled H. teres. Received from A. L. Bakke Jan. 5, 1920. 

 Culture isolated Jan. 9, 1911. 



H. No. 4. Isolated by F. L. Stevens Jan. 16, 1920, from specimens 

 from Iowa labeled H. teres. 



H. No. 5. Isolated by F. L. Stevens Jan. 16, 1920, from barley, 

 from specimen from Iowa labeled H. gramineum. 



H. No. 6. From E. C. Stakman, Jan. 20, 1920. Isolated from 

 blighted seedling of Marquis wheat. 



H. No. 7. From E. C. Stakman, Jan. 20, 1920. Isolated from 

 Marquis wheat. 



H. No. 8. From E. C. S. (E. C. Stakman), Jan. 20, 1920. Isolated 

 from Marquis wheat growing in sterile soil. 



H. No. 9. From E. C. S., Jan. 20, 1920. Isolated from roots of 

 Marquis wheat seedlings. 



