Unfortunately, I was only able to locate
one of the 45 photographs of the heads published in 1906 and 1909 by the Viennese photographer Josef Wlha (1842–1918). These images are definitely in public domain by now and would cover most of the remaining lacunas (heads Nos. 4, 31, 41, 49 are not part of the portfolio). Perhaps, someone will have better luck with this, so here are the references:
Josef Wlha (1906) Franz Xaver Messerschmidt: Charakterköpfe
Josef Wlha and Ludwig Hevesi (1909) Franz Xaver Messerschmidt's Werke
Unfortunately, I was only able to locate
one of the 45 photographs of the heads published in 1906 and 1909 by the Viennese photographer Josef Wlha (1842–1918). These images are definitely in public domain by now and would cover most of the remaining lacunas (heads Nos. 4, 31, 41, 49 are not part of the portfolio). Perhaps, someone will have better luck with this, so here are the references:
Josef Wlha (1906) Franz Xaver Messerschmidt: Charakterköpfe
Josef Wlha and Ludwig Hevesi (1909) Franz Xaver Messerschmidt's Werke