134 Barlow J Hancock^ and Lacey 



Table 2. The effect of different inhibitor concen- 

 trations on the length {n) of pollen tubes of two apple 

 varieties growing in 10 per cent sucrose; average of 

 solutions containing 0, 1, and 5 p. p.m. 1-naphtha- 

 leneacetic acid. 



was reduced. Table 2 shows the results of two experiments averaged 

 together. 



It is of interest that the highest inhibitor concentration, which 

 would have a drastic effect on coleoptile section extension, has al- 

 lowed quite an amount of growth by pollen tubes. These test ob- 

 jects were too delicate to wash and transfer to inhibitor-free solution 

 to find out if recovery could occur. 



Extension of Cress Roots 



Cress seeds were grown on damp filter paper at 25° C. for 2 days, 

 and those with radicles 5 to 7 mm. long selected (11), and placed, 

 five in a line, on filter paper in petri dishes sloped at ca. 45°; 2 ml. 

 solutions were applied to the papers, and the root length measured 

 after 48 hrs. at 25° C. In another method, 20 seeds were sown di- 

 rectly onto filter paper wetted with the solutions, an extra ml. being 

 added to allow for the water taken up by the gelatinous seed coats. 



Results with either method have always been very variable, but 

 from a large number of tests it is possible to say with certainty that 

 the inhibitor does not function as an anti-auxin, neither promoting 

 root growth at any concentration, nor relieving the inhibition due 

 to NalAA. 



Fungal Growth 



The inhil)itor, even at 100 ints/ml, had no effect on the growth of 

 Pulularia puUulans (a saprophytic ascomycete), J'ryticilliinn albo- 

 atnim (a pathogenic ascomycete), or an imidentified yeast, in tests 

 kindly carried out by the Plant Pathology Section of this station. 



Ab.scission 



Three experiments, with three clones of Coleus sp. in each, failed 

 to detect any effect of inlnbitor on the abscission of debladed petioles 



