498 PATHOGENIC MICROORGANISMS 



immune animals. The most widely used method of producing such 

 serum is that of Maragliano. 



Maragliano's Serum.' — Maragliano believes that a toxalbumin is 

 present in tubercle-bacillus cultures which is destroyed by the heating 

 employed in the usual tuberculin production. He procures this sub- 

 stance by filtration of unheated cultures and precipitation with alcohol 

 (tossina pracipitata). He furthermore makes an aqueous extract of 

 the bacillary bodies. With these two substances he immunizes horses. 

 He draws blood from these after four to six months of treatment. The 

 serum is extensively used in Italy. Its value is, at present, very 

 doubtful. 



Marmorek's Serum? — Marmorek claims that the poisons produced by 

 Bacillus tuberculosis depend largely upon the mediiun on which it is 

 grown. He advanced the view in 1903 that the substances obtained 

 in tubercuHn were not the true toxins of the tubercle bacillus, that there 

 was a marked difference between these and the poisons elaborated by a 

 younger (primitive) phase of the bacillus as it occurs only within the 

 animal body or on media composed of animal tissue. He consequently 

 grows his cultures on a medium composed of a leucotoxic serum (pro- 

 duced by inoculating calves with guinea-pig leucocytes) and liver tissue. 

 Such cultures, he claims, contain no tuberculin. To the sera produced 

 by immunization with these cultures he attributes high curative powers. 



Bacilli Closely Related to the Tubercle Bacillus. — The Bacillus of 

 Bovine Tuberculosis. — Tuberculosis of cattle (Perlsucht) was studied 

 by Koch' in connection with his early work on human tuberculosis. 

 Koch did not fail to recognize differences between the reactions to in- 

 fection in the bovine type of the disease and that of man. He attrib- 

 uted these, however, to the nature of the infected subject rather than 

 to any differences in the infecting agents. This point of view met 

 with little authoritative contradiction, until Theobald Smith,^ in 1898, 

 made a systematic comparative study of bacilli isolated from man and 

 from cattle and pointed out differences between the two tj^^es. The 

 opinion of Smith was fully accepted by Koch ^ in 1901. 



Since that time, the question, because of its great importance to 

 prophylaxis, has been the subject of many investigations, most of them 



' Maragliano, Berl. klin. Wooli., 1899; Soc. de biol., 1897. 



' Marmorek, Berl. klin. Woch., 1903, p. 1108; Med. Klinik, 1906. • 



' Koch, Arb. a. d. kais. Gesundheitsamt, 11, 1882. 



* Th. SmUh, Jour. Exp. Med., Ill, 1898. 



s Koch, Deut. med. Woch., 1901. 



