180 



then laid on the unrolled doll and inoculation made in the desired man- 

 ner. The doll was then rolled up, inclosing the seedlings, and placed 

 again in the test-tube. For purposes of root inoculation the doll was 

 suspended in the test-tube about five centimeters from its bottom. 



Inoculations in soil. In addition to the usual pot and bench inocu- 

 lations, it was found convenient to use wide-mouth vials, 12X70 mm. 

 (see page 128), which were lined with stiff paper (so cut as to open easily, 

 PI. XXXIII), filled with soil, and autoclaved. The paper envelope with 

 the enclosed soil could readily be withdrawn from the vial, and opened in 

 order to insert the seed, seedling, or inoculum, and later repeated exam- 

 inations could be made without greatly disturbing the plant. 



Imbedding conidia. Conidia were raised under standard conditions 

 (see next paragraph) and the entire shoot bearing them, together with 

 the adjacent agar a strip about 4 mm. wide was removed to chrome- 

 acetic killing-fluid, and imbedded in the usual way. 



Procedure to secure standard conditions. Petri dishes of 12 c.c. washed 

 agar, when solid, were inoculated in the center with the desired organism. 

 When, in the course of a few days, this had attained a colony-diameter 

 of 2 to 3 cm., wheat shoots, autoclaved in water, were laid on the surface 

 of the agar, the basal ends of the shoots touching the edge of/the advanc- 

 ing colony. Usually about six shoots were used per plate, resulting in 

 ample material. Aseptic wheat shoots were secured by the method 

 described in the next paragraph. The shoots were cut for autoclaving 

 when they were about 2-3 cm. in length. This medium was selected 

 as being of appropriate composition and only very slightly variable. The 

 washed agar in uniform quantity in Petri dishes of the same depth gave 

 a uniform humidity, while the mode of inoculation was also uniform, 

 doing away with many errors that arise when the quantity of the inoculum 

 is a variable factor. 



Growing aseptic seedlings. Seeds were treated three hours in 20% 

 fresh Javelle water, rinsed with sterile distilled water, and germinated 

 on damp filter-paper in moist chambers (44). In the latter part of the 

 study para-toluene-sodium-sulphochloramide was substituted for Javelle 

 water in seed-disinfection. It was used in 0.5% aqueous solution, the 

 seeds being immersed for twenty minutes. Such preliminary tests as 

 we have made, indicate that a solution of 0.25 to 0.5% is efficient as a 

 fungicide, while such solutions may be safely used without injury to the 

 grain. It certainly possesses value for such uses in the laboratory, and 

 may be of service as a fungicide in other connections. A rather 



