The search for a reliable mounting medium for Recent ‘live’ foraminifera

Abstract. There is no suitable mounting medium for the longterm storage of Recent, ‘live’ foraminifera. Glycerol has been used for this purpose since the last century, but its properties do not meet our requirements (see below). We therefore began a series of trials in order to find the ‘perfect’ mountant. The inception of this ‘Micropalaeontological Notebook’ provides a timely opportunity to highlight the results of our experiments and to elicit a response from the readership to facilitate our search.

In choosing mounting media for experiment it was first necessary to detail our requirements. The latter are as follows: the medium must be clear and possess a refractive index (nD:) close or equal to that of glass. The nD of the mounted specimens should differ from that of the mountant or they will be invisible. It should function as a permanent mount, fixing specimens in a position suitable for light microscopical examination. It should not form aggregations or induce overlap of specimens and should permit easy relocation of small organisms (i.e., fixing them so that their co-ordinates can be read with an England Finder) It should neither be messy nor aspirate air and should not contract, thereby crushing delicate specimens. The mountant must be treated to inhibit bacterial and fungal growths. It must be relatively inexpensive and quick to prepare and must not solidify too rapidly, leaving insufficient time to position specimens. Since the specimens are ‘live’ it is important that the protoplasmic contents of the cell and the mountant are isotonic. Similarly, . . .