ALBERT C. HILDEBRANDT 395 



increased weight of the normal cultures with corresponding increases 

 in concentrations from I0-^ lo"^ . . . iQ-^ The greatest weight appeared 

 at a concentration of 10"^ Indole-3-acetic acid was not necessary for the 

 culture of the crown-gall tissue, and the above concentrations had no 

 effect on the wet weight of the cultures although a concentration of 

 io~* resulted in a decreased wet weight as compared with controls lacking 

 the supplement. Gautheret (9) similarly compared the responses of 

 normal tissue, tissue of crown-gall origin, and of habituated tissues of 

 black salsify to varying concentrations of indole-3-acetic acid. The 

 tissues of crown-gall origin and the habituated tissues compared with 

 the controls lacking indole-3-acetic acid were unaltered with respect 

 to the increase in wet weight at concentrations from io~^, lo"'' . . . 

 I0-^ but were inhibited at a concentration of 10-*. Both these tissues 

 are capable of unUmited growth on media lacking growth-regulating 

 substance. The normal tissue however was strikingly stimulated as evi- 

 denced by the progressively increased wet weight through progressively 

 increased concentrations of indole-3-acetic acid from lo""^, lo"'' . . .io~^ 

 The results with the salsify normal and crown-gall tissues were therefore 

 comparable to similar tissues of Jerusalem artichoke. 



Recently Kulescha and Gautheret (15) compared the amount oi 

 growth-regulating substance elaborated by the three strains of tissue 

 from black salsify. Ether extracts were prepared of the three tissues 

 and Avena tests made in the usual manner. On a wet-weight basis 

 normal root tissues extracted in January during the resting period con- 

 tained activity corresponding to 0.5 x io~^ of indole-3-acetic acid. Similar 

 tissue isolated and placed on a medium-lacking growth-regulating sub- 

 stance had after seven days activity equal to o.i x lo"^ indole-3-acetic 

 acid. Such tissue that produced buds after 10 days had an activity 

 equivalent to 1.5 x I0~^ but if the buds were removed the concentra- 

 tion decreased to from 0.2 to 0.3 x 10"^ Tissue of crown-gall origin 

 had much greater activity indicating a concentration equivalent to 

 5.3 to 5.5 X iQ-^ Similarly, the habituated salsify tissue had activity 

 equivalent to 1.5 to 2.3 x iq-^ The concentrations of growth-regulating 

 substance therefore in these latter two tissues corresponded to the con- 

 centrations found earlier to be optimum for callus formation in tissues 

 from a variety of species (5) and suggested why such tissues required 

 no supplementary growth-regulating substance. Tissues of crown-gall 

 origin and habituated tissues had similarities and differences as compared 



