during fine structure analyses of artificially induced waxy mutants in maize by use of nelson 's pollen analysis methods , it was noticed that some mutants showed a phenotype intermediate between waxy and normal nonwaxy . 
 such intermediate or leaky waxy mutants were frequent among mutants induced by a chemical mutagen , ems . 
 they seemed to be located evenly within the waxy locus . 
 this would suggest that they might have been missense mutations , which would produce full - sized but partially inactivated enzymes , rather than deletions or frameshift mutations . to confirm the intermediate phenotype 
 , a rapid measuring system was developed to measure waxiness of endosperm quantitatively . 
 it was based on the blue value method and is applicable to a single grain of rice . among the 27 waxy mutant lines of maize , including 11 
 ems - induced , two of the ems - induced mutants were clearly intermediate . 
 eighteen ems induced wx mutants of rice were also examined , and nine were intermediate.imagesfigure 1 .