[18] In the author’s laboratory in the past ten years all sterilization except those few objects in blood and serum work which must be dry, has been done in autoclaves of the type shown in Fig. 81 which are supplied with steam from the University central heating plant. A very great saving of time is thus secured. [19] The author has tested an “electric milk purifier” (Fig. 102) which was as efficient as a first-class pasteurizer and left the milk in excellent condition both chemically and as far as “cream line” was concerned. The cost of operation as compared with steam will depend on the price of electricity. [20] The exact laboratory details for preparing various media are not given in this chapter. It is the object to explain the choice of different materials and the reasons for the various processes to which they are subjected. [21] For a discussion of this method of standardization consult the following: Clark & Lubs--J. Bact., 1917, II, 1-34, 109-136, 191-236. Committee Report--Ibid., 1919. IV, 107-132. Jones--J. Inf. Dis., 1919, 25, 262-268. Fennel & Fisher--Ibid., 444-451. Additional references will be found in these articles. [22] Term also applied to the solidification of serum in media: _e.g._, the Hiss inulin medium for the differentiation of pneumococci (see diplococcus of pneumonia). [23] The term “antigen” is also used to designate substances which may take the place of what are supposed to be the true antigens in certain diagnostic reactions (Chapter XXIX, Complement Fixation Test for Syphilis). [24] If the antitoxin is later concentrated (see last paragraph in this chapter) a serum containing as little as 175 units per cc. may be commercially profitable. [25] Tho term “allergie” was introduced by Von Pirquet to designate the state of the animal’s being sensitized and “allergic” as the adjective derived therefrom. It does not seem to the author that there is any advantage gained by the introduction of these terms. INDEX A ABBÉ, 17 condenser, 200 microscope, improvements in, 30, 36 ABILGAARD, 26 Abrin, 262 Absorption of free nitrogen, 117 tests, 267 Accidental carriers, 241 structures, 43 Acetic acid, 99 bacteria, carbon oxidation, 114 fermentation, 32 _Acetobacter acidi oxalici_, 83 _xylinum_, 83 _Achorion schœnleinii_, 27, 34 Acid, acetic, 99 fermentation, 32 agglutination, 266 amino, relation to green plants, 119 butyric, 99 fermentation, 32, 99 carbolic, first used, 29 disinfectant action of, 159 fast bacteria, fat content, 84 staining of, 209 fermentation, 93 Bulgarian fermented milk, 98 ensilage, 98 industrial uses, 97 lactic acid, 96 sauerkraut, 98 hydrochloric, 246 production of, 110 soils, 81 Acquired immunity, 251, 252 _Actinomyces bovis_, 30, 36 Actinomycosis, cause of, 30, 36 path of entrance of, 244 Actions, reducing, 113