Histology Library collection

The sections have been made from various plant organs, by hand or microtome, in some cases dyed, and mounted in resin (rather like fossils set in amber) between a slide and a strip of glass. The preparations are stored in grooved boxes and arranged like books, or in the case of the oldest ones, laid flat in the drawers of special glass-fronted units. This is the case for the core collection, created by Philippe Van Tieghem and his students from 1875 to 1914, which contains around a third of the Histothèque slides.

Sometimes the preparations are the only illustration available for a study, as no figures or photos have been published, particularly for the works written by Louis Pierre and P. Van Tieghem between 1890 and 1902 on the Sapotaceae and Ochnaceae respectively, describing many new genera based on anatomical characteristics. Very often, type material – sometimes taken from the Historical Herbaria – has been used. There are plans to introduce modern technologies (digital photos and computerisation) in order to make the most of this rich heritage, which for the moment is not easily accessible as these sections can only be observed on site through a microscope. Creating an associated image bank in the SONNERAT database will make it easier to share this type of information with specialists. The role of the Histothèque is to store plant tissue for purposes of comparison and expert appraisal in relation to other collections, some of which are unique in the world (the Easter Island woods for example).

The recent collections (since 1960) more commonly use the Alcoothèque material and the paraffin inclusion method, enabling the creation of thinner sections (between 20 and 5 µm) which are better oriented and may be serial sections (particularly for floral anatomy). Placed in boxes, they can easily be stored in a compactus, like herbarium specimens. The reinstallation of the Histothèque considerably improved its accessibility for consultation and prompted us to consider deposits from other collections of worldwide interest. Indeed, universities do not always have the premises, staff or equipment to maintain and derive value from their plant anatomy collections. This is an international problem, which in some countries leads to this type of collection being destroyed.

The main benefit of these permanent preparations - which are very often dyed with carmine alum and iodine green, and perfectly labelled - is that they are always connected to published research works that can be used for reference.

For around thirty years, research has focused on comparative floral anatomy (particularly the Magnoliales, Asparagaceae and Convolvulaceae). The results obtained in the laboratory are useful for interpreting field observations on pollination and fertilisation, as well as establishing the phylogenies of these groups.

Thierry Deroin
thierrry.deroin [@] mnhn.fr