Three homologous series of Schiff's base compounds have been prepared to investigate the relationship between chemical constitution and mesomorphism, by condensingp-n-alkoxybenzaldehydes withp-n-propoxy-,p-n-butoxy-andp-n-amyloxyanilines respectively and the various transition temperatures are recorded. These series exhibit the general mesomorphic properties as found in other analogous series. It is found that the lower homologues are either non-mesomorphic or nematic while middle members are smectic and nematic both and the higher homologues are purely smectic. In many homologues polymesomorphism in smectic phase is observed.