272 Teubner, Wittwer, and Shen 



cept the thesis that time of flowering is the essential criterion, as Gor- 

 ter (Proc. Kon. Ned. Akad. v. Wetensch. 52: 1185. 1949) apparently 

 does in her studies with triiodobenzoic acid, then we are not affecting 

 flower initiation. 



Dr. Gowing: Dr. Nitsch might be interested to know that the ma- 

 terial does not induce flowering in pineapple, in contrast to a number 

 of other compounds with auxin activity. However, it does have very 

 marked formative effects. It leads to a closed tube of leaf tissue rather 

 than the normal open channel-like leaf of the pineapple plant. If 

 dichlorophenylphthalamic acid is applied about the time of natural 

 inflorescence differentiation, it leads to a reduction in the number of 

 fruitlets contributing to the multiple fruit, and a corking between the 

 fruitlet tissues. The effect is somewhat similar to that reported by 

 Muzik and Cruzado (Plant Physiol. 31: 81. 1956) for maleic hydrazide 

 on pineapple in Puerto Rico a few years ago. 



Dr. Wain: Have any compounds been made from substituted 

 phthalic anhydrides? 



Dr. Teubner: We are investigating a number of these, Avith chloro- 

 and nitro-substituents on the phthalic ring. These have not been 

 studied with respect to activity in all three tests, since the tomato 

 flowering tests and parthenocarpic fruit tests are quite time consum- 

 ing. As Dr. Wain pointed out earlier, it's best to examine a whole 

 series of compounds before drawing conclusions as to structure- 

 activity relationships, and we have insufficient information to com- 

 ment on the effect of substitution in the phthalic ring. 



