(a) Prepare cover-slip film preparations at the various ages, and fix by exposure to a temperature of 115° C. for twenty minutes in hot-air oven. (b) Stain the preparations by Gram's method (if applicable) or with dilute carbol-fuchsin, and mount in the usual way. (c) Measure (_vide_ page 66) some twenty-five individuals in each film by means of the Ramsden's or the stage micrometer and average the result. _Pleomorphism_; If noted, record-- The predominant character of the variant forms. On what medium or media they are observed. At what period of development. (b) To demonstrate details of _structure_: _Flagella_: If noted, record-- Method of staining (_vide_ page 101). Position and arrangement (_vide_ page 136). Number. _Spores_: If noted, record-- Method of staining. Shape. Size. Position within the parent cell. Condition, as to shape, of the parent cell (_vide_ page 139). Optimum medium and temperature. Age of cultivation. Conditions of environment as to temperature, atmosphere. Method of germination (_vide_ page 140). _Involution Forms_: If noted, record-- Method of staining. Character (e. g., if living or dead). Shape. On what medium they are observed. Age of medium. Environment. _Metachromatic Granules_: If noted, record-- Method of staining. Character of granules. Number of granules. Colour of granules. ~3. Staining Reactions.~-- 1. _Gram's Method._--Positive or negative. 2. _Neisser's Method._--If granules are noted, record-- 1. Position. 2. Number. 3. _Ziehl-Neelsen's Method._--Acid-fast or decolourised. 4. _Simple Aniline Dyes._--(Noting those giving the best results, with details of staining processes.) Methylene-blue } Fuchsin } and their modifications. Gentian violet } Thionine blue } BY BIOCHEMICAL METHODS. Test cultivations of the organism for the presence of-- Soluble enzymes--proteolytic, diastatic, invertase. Organic acids--(a) quantitatively--i. e., estimate the total acid production; (b) qualitatively for formic, acetic, propionic, butyric, lactic. Ammonia. Neutral volatile substances--ethyl alcohol, aldehyde, acetone. Aromatic products--indol, phenol. Soluble pigments. Test the power of reducing (a) colouring matters, (b) nitrates to nitrites. Investigate the gas production--H_{2}S, CO_{2}, H_{2}. Estimate the ratio between the last two gases. Prepare all cultivations for these methods of examination under _optimum_ conditions, previously determined for each of the organisms it is intended to investigate, as to (a) Reaction of medium; (b) Incubation temperature; (c) Atmospheric environment; and keep careful records of these points, and also of the age of the cultivation used in the final examination.