Abstract: Pollen calli were subcultured for 20 months. According to the degree of totipotency observed during this period they can be divided into the following four types: 1) The potential of differentiation of the calli was lacking. 2) The calli were able to differentiate into a few root-like structure and green spots. 3). The calli were able to grow into not only a few green spots but also a few shoots. But they could not develop into normal plants. 4). This type of callus possessed a great ability of differentiation and regeneration. They could develop into embryoids as well as shoots in the same medium. After transferring on to the regeneration medium, they readily regenerated into green plantlets with profuse roots. When chromosome counts were made on the ealli, it was found that variations in ploidy were not great. From 1539 randomly chosen cells at metaphase stage, 90% were haploid. As the counts were made on the No. 1 callus type and the root-tip cells of the 35 pants regenerated from this same type 89.7% of the former 427 cells and 87.4% of the latter 645 cells were determined to be haploid. The calli of the Type No. 1 possess unlimited totipotency demonstrated by regeneration. These stability and totipoteney may play an important role in practical application and theoretical research of maize.