38 J. A. Bentley 



acteristic color reactions, in particular a dark blue Ehrlich reaction. 

 It has not been located in any of the other algae. A blue Ehrlich re- 

 action usually denotes that there is substitution of an OH- or OR- 

 group at position 5 of the indole nucleus. 



Another interesting indole compound was located in Clilorella. 

 This gives a purple Ehrlich reaction, a red Salkowski and orange ni- 

 trous-nitric acid reaction. It has an unusually low Rj of approxi- 

 mately 0.12 in ammoniacal isopropanol. It runs at Rf 0.5 in water, 

 with soine streaking, which suggests that it may be polyionic. It is 

 not indole-3-acetylaspartic acid, which runs at Rf 0.83 in water, nor 

 is it malonyltrytophan, which has an Rf of 0.95 in water, and gives 

 a brown Salkowski reaction. Nor is it likely to be indole-3-pyruvic 

 acid, which remains very close to the starting line on chromatography 

 in water. From the Ehrlich reaction, it is unlikely to be a 5-hydroxy 

 indole compound. 



Some consideration was given to whether indole-3-acetamide oc- 

 curred in zone Z, since this has been shown to be produced during 

 ammoniacal chromatography of indole-3-pyruvic acid and other na- 

 tural indoles (7). Indole-3-acetamide has only slight biological activ- 

 ity (about 1 per cent that of lAA), which is unlikely to account for 

 all the activity located in zone Z. Also it runs at a sliglitly lower Rf 

 than zone Z in ammoniacal isopropanol, and no activity is located in 

 the lAA region (eqiuvalent to zone X) on rechromatography. 



It is noteworthy that there is no evidence of either the a-accelcr- 

 ator (close to the starting line) or the (3-inhibitor (just ahead of lAA) 

 in any of the algal extracts examined. 



SUMMARY 



Auxin activity has been located in extracts of the following — 

 Chlorella pyrenoidosa, Oscillator ia spp., and Ochromonas malhanien- 

 sis. 



Two fractions of the extracts have been examined in detail, the 

 acidic ether-soluble fraction, and the aqueous ether-insoluble fraction 

 after saponification in alkali and extraction with ether. Two active 

 zones, tentatively labeled X and Z, have been located in both frac- 

 tions of all the species examined. These are not necessarily due to 

 the same substances in both fractions but this appears likely, since 

 X and Z in both fractions show a mutual interconvertibility. The 

 intcrconvertibility suggests that the compounds may be closely related 

 chemically. There is also evidence of activity in a zone (Y) intermed- 

 iate between X and Z. The interconvertibility of zones X, Y, and Z 

 has been noted previously in extracts of tomato roots, and a similar 

 phenomenon is reported recently by workers using pea roots. These 



