A Methods Manual for the Collection, Preparation and Analysis of ...

6. What can you expect to see when viewing a prepared diatom slide?A series of neatly aligned pictures that have been cropped and graphically enhanced arenormally displayed to illustrate diatom taxa in books, manuals and guides. Whole cells areusually illustrated in valve view in such guides and most of the morphological characteristicsare visible. Fragments or broken pieces are not normally shown. However, your slides willhave diatom cells that are orientated at different angles, often lying obliquely or in girdle viewand some may be damaged or fractured fragments. Different types of microscope illuminationmay also provide slightly different images to those found in routine identification guides.1 23 45 6a 6bFig. 1 shows a scattered slide mount of diatoms under low magnification. Fig. 2 shows the samemount under high magnification (x1000) using incident light. Fig. 3 shows the same as Fig 2 but agreen filter is used to increase contrast. Fig. 4 shows the use of differential interference (DIC) optics.Fig. 5 shows the use of Phase contrast optics and Fig 6a shows Fig. 4 correctly orientated, croppedand converted to greyscale, while 6b shows digital enhancement and contrast correction.9