Lamarck based his description of the newly named species on plant specimens collected in India. Histology has also allowed the age of other specimens to be determined. Rapid diagnostic assays performed on respiratory specimens are available commercially. Adult specimens weighing over are not uncommon. The main museum contains huge collections of archaeological specimens and fine art. He also preserved a few of his specimens. This study showed that 9.8% of "Stegosaurus" specimens examined had injuries to their tail spikes. Another species of "Pterodactylus" originally based on small, immature specimens was "P. micronyx". Dark field microscopy is a technique for improving the contrast of unstained, transparent specimens. The largest measured specimens have been long and . Low voltage increases image contrast which is especially important for biological specimens. Several other specimens from diameter are known. The exhibit is famous for its large, touchable rock specimens. But Merian was not interested in preserving, collecting or studying specimens. There are also problems involved in the collection of specimens and issues of contamination.