Effect of the Waxy Gene in Maize Pollen,-a Reply to Criticisms.

It was independently discovered and coincidentally reported by DEMEREC (1924) and by BRINK and MACGILLIVRAY (1924) that maize pollen grains carrying the waxy gene give a unique reaction with the iodine-potassium-iodide solution commonly employed in detecting starch. LONGLEY (1924) has also reported this phenomenon. In a recent paper, KIESSELBACH and PETERSEN (1925) question the validity of our observations and conclusions. I n our original papers we showed that pollen of flint, dent, pop and sweet varieties of maize contain reserves giving the well-known blue reaction characteristic of starch when tested with iodine. On theother hand, the contents of pollen grains produced by homozygous waxy plants fail to give this blue color when similarly treated, but stain a dull yellow passing to reddish under conditions favoring gradual concentration of the test solution. It was found, moreover, that individuals heterozygous for the waxy character produce both types of pollen grains, namely, bluestaining and yellowish-staining, in approximately equal numbers. This significant fact we took to indicate an immediate effect of the segregation of the non-waxy-waxy allelomorphs. KIESSELBACH and PETERSEN have been unable to demonstrate this difference in the nature of waxy and non-waxy pollen and hold that it does not exist. Their observations and conclusions may be briefly summarized as follows: (1) Normally-developed mature pollen from waxy as well as from non-waxy races of maize gives the starch reaction with iodine. (2) The iodine solution does not serve to differentiate the content of the pollen grains of waxy and non-waxy maize. ( 3 ) The walls of the immature pollen of all varieties assume a reddish color with iodine which