74 Fawcett, Wain, and IVightmati 



The compounds were dissolved in water containing 0.1 per cent ace- 

 tone and were examined at five concentrations ranging from lO'^M to 

 10-8M. 



Wheat Cylinder Test 



Ten-mm. sections excised from 2-cm. coleoptiles of 3-day-old 

 wheat seedlings ('Eclipse') were used as the experimental material. 

 The sections were threaded on glass capillaries and floated on the test 

 solutions contained in petri dishes, ten sections per dish. After 24 hrs. 

 treatment at 25° C, the length of the test sections was determined and 

 the results are presented as a percentage of the final length of water 

 controls. 



Pea Segment Test 



Five-mm. segments excised from the second internode of 6-day-old 

 pea plants ('Alaska') were used as test material. The seedlings were 

 grown in sand under red light at 25° C, and the second internode 

 was approximately 2 cm. in length when the test segment was re- 

 moved. Batches of ten segments were placed in petri dishes on filter- 

 paper bridges supported by two glass rods, the ends of the filter paper 

 dipping into the test solution and serving as a wick for supplying 

 solution to the segments. After 24 hrs. treatment at 25° C, the seg- 

 ments were measured under a microscope and the results are again 

 presented as a percentage of the final length of water controls. 



Pea Curvature Test 



Three-cm. segments were excised from the second internode of 

 young pea plants ('Alaska') grown for 7 days as described above. Each 

 segment was split longitudinally with a razor blade for approximately 

 2 cm. through its upper elongating region, and after washing in water 

 for 2 hrs., five split segments were placed in each test solution for 24 

 hrs. at 25° C. The curvatures induced were assessed by a numerical 

 scale from (inactive) to 6 (highly active) similar to that suggested by 

 Went and Thimann (10). 



In the metabolism experiments, solutions of each compound were 

 exposed to wheat coleoptilc or pea stem tissue with subsccjuent ex- 

 traction and paper chromatograj)hic analysis of the products present 

 in the tissue and in the residual solution. For each treatment, 100 

 1-cm. coleoptile segments or 50 I-cm. pea stem segments were placed 

 in a petri dish containing 1,000 y^ig. of the compound in 50 ml. of 

 distilled water, the solutions being then incubated in the ilark for 48 

 hrs. at 25° C. It was usual to metabolize 4,000 /xg. of each compound 



