790 A. S. Crafts 



Table 1 . Absorption and translocation of 2,4-D as shown by bean bending. 



cate that repression of dissociation enhances uptake via a lipoidal 

 route by making the applied chemical more lipoid soluble. More 

 recent work (3) has shown this same relation to hold for 2,4-D, Table 



I. Endothal is another compound that benefits from acidification of 

 the formulation. 



Work with maleic hydrazide (MH) by Zukel and associates (13) soon 

 proved that acidification of this compound was of no avail, Table 2. 

 Trials with the parent compound and with ester formulations like- 

 wise failed to improve uptake (7), Table 3. The fact that at present 

 the only way to increase uptake of MH is to place the plant in a 

 saturated atmosphere would seem to indicate that there are two dis- 

 tinct routes by which chemicals applied to leaves may move into the 

 vascular channels, a lipoid route and an aqueous route. MH moves 

 via the latter. 



Considering first the lipoid route, it seems evident that the spray 

 solution must wet the cuticle. From this solution the regulator mole- 

 Table 2. Weight in grams of growth of 'Bermuda' grass shoots sprayed January 



II, 1951, with 0.5 per cent MH (DEA) adjusted to a series of pH values. (Values are 

 averages of duplicate cultures.) 



