1) The stored tobacco pollen was sown on the artificial medium (10% water solution of cane sugar), and compared their germinating percentage with the fertilizing power. The fertilizing power was shown by the fertilizing percentage resulted by the pollination with these stored pollens. 2) As it is well known, the germinating percentage decreased as the pollen became older, and the fertilizing percentage also decreased in the same manner. But there were some differences observed between these two cases. Namely, the decrease of the former was rapid than that of the latter. In other words, the pollen which could fertilize the egg was often not able to germinate on the media. 3) It is sometimes reported that the pollen, stored under dry condition, germinated better in the case of pretreatment was made by keeping them in a moist chamber for a short time, than in the ordinal case of setting them directly upon the medium. In this study, the author hold the dry stored pollen grains in a moist chamber for 30 minutes to make them absorp the moisture, and set them on the media as well- as on the pistils. The germinating percentage on the media increased by means of this pretreatment, but the pollen which passed the practical storing period or the dead pollen could not germinate even if such treatment, above mentioned, was made. In the case of the pollination was made upon the pistil, the effect on this pretreatment can be observed neither on the fertilizing percentage nor on the longevity of fertilizing power.