Leaf parasites, whether on living or dead leaves, may be dried in the usual way for drying plants, between folds of bibulous paper under pressure. It may be sometimes necessary with dead leaves to throw them in water, in order that they may be flattened without breaking, and then dry them in the same manner as green leaves. All species produced on a hard matrix, as wood, bark, etc., should have as much as possible of the matrix pared away, so that the specimens may lie flat in the herbarium. This is often facilitated in corticolous species by removing the bark and drying it under pressure.
The dusty _Gasteromycetes_ are troublesome, especially the minute species, and if mounted openly on paper are soon spoiled. A good plan is to provide small square or round cardboard boxes, of not more than a quarter of an inch in depth, and to glue the specimen to the bottom at once, allowing it to dry in that position before replacing the cover. The same method should be adopted for many of the moulds, such as _Polyactis_, etc., which, under any circumstances, are difficult to preserve.
In collecting moulds, we have found it an excellent plan to go out provided with small wooden boxes, corked at top and bottom, such as entomologists use, and some common pins. When a delicate mould is collected on a decayed Agaric, or any other matrix, after clearing away with a penknife all unnecessary portions of the matrix, the specimen may be pinned down to the cork in one of these boxes. Another method, and one advisable also for the _Myxogastres_, is to carry two or three pill-boxes, in which, after being wrapped in tissue paper, the specimen may be placed.
A great difficulty is often experienced with microscopic fungi, such, for instance, as the _Sphæriacei_, in the necessity, whenever a new examination is required, to soak the specimen for some hours, and then transfer the fruit to a slide, before it can be compared with any newly-found specimen that has to be identified. To avoid this, mounted specimens ready for the microscope are an acquisition, and may be secured in the following manner. After the fungus has been soaked in water, where that is necessary, and the hymenium extracted on the point of a penknife, let it be transferred to the centre of a clean glass slide. A drop of glycerine is let fall upon this nucleus, then the covering glass placed over it. A slight pressure will flatten the object and expel all the superfluous glycerine around the edges of the covering glass. A spring clip holds the cover in position, whilst a camel-hair pencil is used to remove the glycerine which may have been expelled. This done, the edges of the cover may be fixed to the slide by painting round with gum-dammar dissolved in benzole. In from twelve to twenty-four hours the spring clip may be removed, and the mount placed in the cabinet. Glycerine is, perhaps, the best medium for mounting the majority of these objects, and when dammar and benzole are used for fixing, there is no difficulty experienced, as is the case with Canada balsam, if the superfluous glycerine is not wholly washed away. Specimens of _Puccinia_ mounted in this way when fresh gathered, and before any shrivelling had taken place, are as plump and natural in our cabinet as they were when collected six or seven years ago.