THE PARENTERAL INTRODUCTION OF PROTEINS 351 



the dose is as much as 2.5 per cent, of the body weight it 

 kills slowly. The mother's blood kills in doses of 0.5 per 

 cent., and fetal blood in doses of 2.5 per cent. This is not 

 due to biological differences between the blood of the 

 mother and that of the fetus, because one sensitizes to 

 the other as well and in as small doses as to itself, but is 

 due to the relative freedom of the fetal blood from ferments. 

 When human blood is injected into the blood of a guinea- 

 pig the former carries the ferment and the latter supplies 

 the substrate. In the infectious diseases the proteolytic 

 ferment in the blood is increased and consequently the 

 minimum fatal dose is decreased. 



Dehne and Hamburger 1 state that white mice do not 

 produce a precipitin when treated with horse serum, and 

 Celler and Hamburger 2 find that white rats fail to respond 

 to ox serum by elaborating a precipitin. 



Uhlenhuth 3 and Michaelis and Oppenheimer 4 found 

 that when rabbits are repeatedly fed through a tube with 

 egg-white or serum, they develop precipitins. Celler and 

 Hamburger say that this may be due: (1) To injury of 

 the esophagus or stomach by the tube, and the introduction 

 of the protein in this way. (2) To the failure of the secre- 

 tion on account of the unnatural method of feeding. (3) To 

 the direct introduction of the protein into the intestine 

 where, according to Oppenheimer and Rosenberg, 5 serum 

 proteins resist tryptic digestion. 



Celler and Hamburger found that in forced or tube 

 feeding the protein may be absorbed unchanged, on account 

 of the lack of digestive juice. 



Chiray 6 has studied the effects of the administration of 

 heterologous proteins. The intravenous injection of a very 

 small amount of egg-white in rabbits causes, after from ten to 

 thirty minutes, a transitory albuminuria with increase in the 



1 Wien. klin. Woch., 1904, No. 29. 2 Ibid., 1905, xviii, 271. 



3 Deutsch. med. Woch., 1900, p. 734. 



4 Arch. f. Phys., phys. Abt., Suppl.-Band, p. 336. 

 6 Hofmeister's Beitrage, 1903, v, 412. 



6 These de Paris, 1906; Jahresber. d. Tierchemie, 1907, xxxvi, 805. 



