Layered germanium polymers that are semiconductive and demonstrate a strong red or infrared luminescence are produced through the topochemical conversion of calcium digermanide. Since the 4-aminopyrimidine derivatives and the existing antimicrobial active compounds andor insecticidal active compounds are used in admixture, the 4-aminopyrimidine derivatives which are useful as pest control agents, particularly as agri-horticultural pest control agents, need be used in smaller amounts and yet their antimicrobial or insecticidal activity can be improved. The generation of the bubble 12 causes the ejection of a drop 16 of an ejectable liquid through an ejection aperture 5 in each nozzle 3, to effect printing. Consequently, imbalance of changes in the recording elements with time, caused by the differences between the frequencies with which the recording elements are used, can be restricted, thus restricting irregularities on an image.