. A practical treatise on medical diagnosis for students and physicians . cro-organism is examined with a high-power lens, the organisms areseen darting about and across the field with great rapidity in variousdirections. If to 10 parts of a pure culture of certain varieties of infec-tious micro-organisms, 1 part of the serum of a patient suffering fromthat infection is added, the motility of the organisms is checked andclumps appear in the field. The clumps enlarge rapidly and are easilyvisible under a magnifying power of 500 diameters. Serum from patients suffering from other diseases or fro
. A practical treatise on medical diagnosis for students and physicians . cro-organism is examined with a high-power lens, the organisms areseen darting about and across the field with great rapidity in variousdirections. If to 10 parts of a pure culture of certain varieties of infec-tious micro-organisms, 1 part of the serum of a patient suffering fromthat infection is added, the motility of the organisms is checked andclumps appear in the field. The clumps enlarge rapidly and are easilyvisible under a magnifying power of 500 diameters. Serum from patients suffering from other diseases or from healthypatients does not produce agglutination if the proportion of serum toculture in the mixture is 1 to 10 or less. The reaction is specific. Thustyphoid bacilli are not clumped by any serum other than that of a typhoidpatient, or a patient immunized against typhoid fever by a more or lessrecent attack of the disease. Typhoid serum when used with a certaindegree of dilution and examined within a certain period of time clumpsno organism except the typhoid Bouillon culture of typhoid bacilli before the addition of diluted typhoid serum (X 500).After Cabot—serum diagnosis. Serum diagnosis has become a valuable mode of recognition of typhoidfever, paratyphoid fever, Malta fever, yellow fever, tropical dysentery,and glanders. It may be of use in other infections, as cholera and thepneumococcus infections, but these diseases are more accurately diagnosti-cated by other bacteriological methods, and need not be considered here. VI BACTERIOLOGICAL DIAGNOSIS. Three methods of securing the serum reaction are employed : themicro-Bcopic, or quick test of the fluid serum or blood; the microscopic, orquick tesi of the dried blood ; and the macroscopic, or slow test, not invogue ;it present in tin- country, although advocated by Wright in Eng-land. Bach of these methods is of value. The observer should select one ami make it his object to become thoroughly familiar with that
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