GroxL'th Factors in Tomato Fruit 



(")9 1 



1.000 



C A C A 



Fig. 3. Synergistic effect of a syntfietic auxin and 10 per cent (v/v) of tomato juice 

 (TJ) on the growth of the cultures of: normal Helianthus tuberosus tuber tissues 

 (HTN), and Gautheret's strains of habituated (SHH) and crown-gall root tissues of 

 Scorzonera hispanica (SHG). C: controls without auxin. A: = 2,4-dichlorophenoxy- 

 acetic acid (0.1 mg/1). The numbers on top of the black bars give the actual in- 

 creases in mg. of fresh Aveight. (From 25) 



theret's crown-gall strain of Scorzonera hispanica, however, was in- 

 hibited by TJ when small explants were used (3), but stimulated by 

 TJ when larger explants were used (13). It was shown later by Nitsch 

 and Nitsch (24) that this particular crown-gall strain also could be 

 markedly stimulated by TJ even when small explants were used, pro- 

 viding an auxin was added to the medium (see Figure 3). 



Habituated tissues. A preliminary experiment with Morel's ha- 

 bituated strain of Rubus fruticosus indicated a stimulatory effect of 

 canned TJ. Although their fresh weight was much greater, the tissues 

 grown on TJ were not as healthy looking as the controls; they were 

 lightly coloied, granular and friable, instead of being white and com- 

 pact. New experiments, in which habituated strains of Parthenocissus 

 tricuspidata of Morel and Scorzonera hispanica of Gautheret were 

 used, showed only a marked growth inhibition by TJ (3). In these ex- 

 periments no synthetic auxin had been added to the media, because 

 it had been demonstrated that the habituated tissues proliferate very 

 well in culture without added auxin (see 5). However, it was found 

 later that the particular strain of habituated Scorzonera hispanica 

 which had been used had, in fact, reverted to the auxin-requiring 

 type. When a synthetic auxin was added to the media together with 

 TJ, then the growth-stimulating effect of TJ became evident on the 



