“…For pyrolysis using low resolution packed columns the problem of recognizing unique retention times is compounded by the difficulty in ensuring that changes in the resolution of components are not providing false information. It is often not clear just how authors are comparing pyrograms but Garner & Chi Yuan (1964), Cone & Lechowich (1970), Vincent & Kulik (1970, , Sekhon & Carmichael (1972, Taylor (1976) and Emswiler & Kotula (1978) all imply qualitative differences between micro-organisms of varying taxonomic relatedness. It may be significant, however, that, with the exception of Cone & Lechowich (1970) and Emswiler & Kotula (1978), all the studies have been on fungi where one might expect to find more chemical differences, but by the same token, more problems with standardizing the preparation of samples.…”