112 The Nature of Precipitin Reactions 



were lost in a serum subjected to peptic digestion, and the precipitable 

 substance in a serum, which during the first stages of digestion reacts 

 slightly, after a time gives no reaction to precipitins. They found a 

 stage in the action of pepsin when the serum remained coagulable but 

 not precipitable. Rostoski (1902, h. p. 60) found the precipitins to 

 be destroyed by peptic digestion. Michaelis (9, x. 1902, p. 735) found 

 that pepsin and normal HCl, taken separately, exerted no action, but 

 when they acted in conjunction for 1 hour, all the precipitin or pre- 

 cipitable substance in a serum had disappeared. The evidence there- 

 fore with regard to the action of peptic digestion is unanimous. 



Regarding the supposed Precipitins for Peptones. 



Contrary to Tchistovitch (v. 1899), whose experiments will be 

 referred to presently, Myers (14, vii. 1900) claimed to have produced 

 precipitins for peptone. He treated rabbits with solutions of Witte's 

 peptone and obtained what appeared to be an antiserum which pre- 

 cipitated homologous peptone solutions. A curious statement of Mj^ers 

 is that the antiserum lost some of its precipitating power after being 

 heated to 56° C, this being contrary to what has been observed by 

 others regarding the resistance of precipitins to heat (see p. 114). 

 He moreover stated that the heated serum could be markedly reactivated 

 through the addition thereto of fresh normal rabbit serum, although 

 the latter alone had no such effect. Other observers, however, are 

 unanimous in finding that precipitins cannot be reactivated in this 

 manner (see p. 94). Myers found that heating antisera for ox and 

 sheep globulin did not have the same effect as upon the " antipeptone " 

 serum. The only author who appears to have confirmed Myers' observa- 

 tion is Schiitze (von Leyden's Festschrift, 1902, cited by this author in 

 his paper of 6, xi. 1902, p. 804) who claims to have been able to 

 distinguish different peptones, for instance, those obtained from the 

 muscles of man and ox. By treating a rabbit with human peptone 

 (from muscle) he states that he obtained an antiserum which gave a 

 reaction with human peptone-containing urine, derived from a patient 

 suffering from carcinoma of the peritoneum, no reaction being given 

 with normal rabbit serum, nor with anti-ox peptone. The latter, however, 

 gave a reaction with the stomach-washings of the same patient above 

 referred to after a meal of beef. 



As stated above, Tchistovitch was unable to obtain precipitins for 

 peptone, after injecting 10 "/o solutions in doses of 5 c.c. repeatedly into 



