3. Gametophyte factor in chromosome 3. A gamete factor having an adverse effect upon the ability of pollen grains possessing it to effect fertilization has been located in chromosome 3. This new gamete factor is independent of the genetic constitution of the silks and hence is different in this respect from the gamete factors in chromosomes 4 and 5. Pollen with this factor is not visibly different from normal. Approximately 12.7% of the functioning pollen from heterozygous plants carry the gamete factor. The linear order in chromosome 3 is Lg2 A ga with the gamete locus some 10-12 units from A. Presumably it should lie close to etched (et).