644 S. Housley and B. J. Deverall 



act by an auxin-sparing mechanism, one is rejecting a biochemical 

 mechanism by considering data derived from a complex growth phe- 

 nomenon, namely auxin-induced inhibition of growth. Such con- 

 sideration requires caution. Our own work consists of examination 

 of a biochemical reaction; no observations on growth are made. We 

 point out that our results are consistent with Brian and Hemming's 

 growth synergisms obtained with lAA and gibberellic acids at opti- 

 mal and sub-optimal concentrations. 



