Published online by Cambridge University Press: 01 May 2009
The following note is based on two papers by Professor A. G. Nathorst and on further details which he has kindly communicated by letter. For the loan of the block (Fig. 1) thanks are due to Dr. H. Munthe, Secretary of Geologiska Föreningen i Stockholm.
By the term ‘collodion imprint’ is meant the impression of any surface on a thin film of collodion. Such an impression is obtained by letting a drop or two of collodion dissolved in ether fall on the surface to be copied. The ether evaporates rapidly, so that in two or three minutes the film is hard. If it does not of its own accord come loose at the corners, it is easily raised by a needle or sharp knife. It is then lifted on to a glass microscope-slide and preserved dry under a cover-slip held in position by gummed strips of paper or by Canada balsam. When the imprint is very sharp, the film can, if desired, be preserved in glycerine-jelly without its distinctness being greatly affected. Some films may be less successful than others, and some may curl too much, so that it is as well to take more than one imprint. In any case it is advisable to throw away the first made, since it usually retains some dust from the surface of the object, whereas following films will be free from this. If the collodion solution is too thick it may be thinned by the addition of ether or of ether and alcohol.
page 437 note 1 “Kollodiumaftryck” såsom hjälpmedel vid undersökning af fossila växter”: Geol. Fören. Förhandl., Bd. xxix, pp. 221–227, April, 1907. “Über die Anwendung von Kollodiumabdrücken bei der Untersuchung fossiler Pflanzen”: Arkiv för Botanik, Bd. vii, Xo. 4, 8 pp., 1 pl., August, 1907.
page 437 note 2 Buscalioni, L. e Pollacci, G. “L'applicazione delle pellicole di Collodio allo studio di alcuni processi fisiologici nelle piante ed in parhcolar modo alla Traspirazioni,” and “Ulteriori ricerche sull’ applicazione, etc.”: Atti dell’ Istituto botanico dell’ Università di Pavia, ser. II, vol. vii, Milan, 1902Google Scholar
page 438 note 1 “Üeber Thaumatopteris Schenlki Nath.”: K. Sv. Vetenskaps-Akad. Handl., xlii, No. 3, 1907.