1.--Ross’s instrument for cutting thin covering-glass for objects. This apparatus consists of a bent arm supporting the cutting portion of this apparatus, which consists of a vertical rod with a soft cork at one end. A brass arm at right angles carries the diamond parallel with and close to the main rod. 2.--Covering-glass measurer. To measure the thickness of covering-glass, place it between the brass plate and the steel bearing; the long end of the lever will then indicate the thickness on the scale, to 1/50-th, 1/100-th, or 1/1000-th inch. 3.--Brass table on folding legs, with lamp for mounting objects. 4.--Whirling table with eccentric adjustment for making cells and finishing off slides. 5.--Air-pump with glass receiver, 3-1/2-inch brass plate for mounting objects and withdrawing air-bubbles. 6.--Improved table with knife for cutting soft sections. This consists of an absolutely flat brass table, with a square hole to receive the wood, or other matter, on a movable screw, which adjusts the thickness of the section. 7.--Smith’s holder with spring and screw for adjusting pressure when mounting objects. 8.--Cutting diamonds for cell-making and cutting slips of glass. 9.--Writing diamonds for cutting thin covering-glass and naming objects. 10.--Page’s wooden forceps, for holding glass slips or objects when heated, during mounting.] PART II. CHAPTER I. Microscopic Forms of Life--Thallophytes--Pteridophyta, Phanerogamæ--Structure and Properties of the Cell. The time has long since passed by since the value of the microscope as an instrument of scientific research might have been called in question. By its aid the foundation of mycology has been securely laid, and cryptogamic botany in particular has, during the last quarter of a century, made surprising progress in the hands of those devoted to pursuits which confer benefits upon mankind. Little more than thirty years ago practically nothing was known of the life history of a fungus, nothing of parasitism, of infectious diseases, or even of fermentation. Our knowledge of the physiology of nutrition was in its infancy; even the significance of starches and sugars in the green plant was as yet not understood, while a number of the most important facts relating to plants and the physiology of animals were unknown and undiscovered. When we reflect on these matters, and remember that bacteria were regarded merely as curious animalculæ, that rusts and smuts were supposed to be emanations of diseased states, and that spontaneous generation still-survived among us, some idea may be formed of the condition of cryptogamic botany and the lower forms of animal life some eight or ten years after my book on the microscope made its first appearance (1854).