Textures of the molecular orientation of molecules in a Langmuir monolayer of pentadecanoic acid (PDA) are compared with similar textures of monomeric and polymeric pentacosadiynoic acid (PCA) monolayers. Both acids PDA and PCA (monomeric and polymeric) exhibit stripe textures with characteristic modulations of the molecular orientation. Using laser heating, we may cleave or deform the stripes in monomeric PCA. The relaxation of the stripes reveals that the stripes in monomeric PCA are solid stripes with a finite Young's modulus of the order E = 5-30 mN/m in contrast to those in PDA, which are hexatic with a vanishing Young's modulus.