When a spore-print is to be taken, select a fully-grown specimen, remove the stem, place the spore-bearing surface upon the gummed paper, cover tightly with an inverted bowl or saucer, and allow to stand undisturbed for eight or ten hours. The moisture in the plant will soften the gummed surface; the spores will be shed and will adhere to it, making a perfect, permanent print. When the print is plain, remove the specimen carefully and dry the print. Number the print-cards to correspond with the number of the specimen in the “Record of Fungi,” and place them in a box or cover. Some genera shed their spores sooner and more freely than others. A surplus of spores is objectionable. In order to know when a print is plainly made, without disturbing the process, have either a specimen of the same age, or a piece of the one under the bowl, on another piece of gummed paper, covered in like manner. This can be examined and will give the desired information. A little experience will enable the student to obtain good and lasting prints. The large black figures on some calendars, if cut with the white about them, are convenient as trial sheets for spore-printing. Lay the specimen partly on the white, partly on the black. If the spores are light, they show best on black ground, and if colored, they show best on the light. Spore measurements, as given by different observers, vary to such a degree that they are of little value, excepting as determining a few species, but spore shapes and characteristics are of use as a last resort, in accurate determinations. A microscope of considerable power is needed. A metrical scale and table of measures is here given, that the student may have a present guide to such measurements as are given in mycological publications. Measures [Illustration: Decimetre.] 1 Metre 39.371 Inches 1 Decimetre 3.9371 ” 1 Centimetre (C M.) .39371 ” 1 Millimetre (M.M.) .039371 ” 1 Micron (µ) 1 Millionth of a 1⁄25400 of an Inch. Metre 1 Line (″) 1⁄12 of an Inch 1 Gramme 15.433 Troy Grains 1 Decigramme 1.543 ” ” 1 Centigramme .1543 ” ” 1 Milligramme .01543 ” ” [Sidenote: Use of Charts of Genera.]