Coexistence imth Precipitable Substances 131 



namely the coexistence of the interacting bodies in the supernatant 

 fluid after a precipitum has formed. Hamburger (6, XI. 1902, p. 1190) 

 has also found this to be the case ; the Qg^ albumin may, however, 

 be found as readily in rabbits which have received their first injection 

 as in those which are immune. The Qgg albumin appeared in their 

 sera two hours after injection, and disappeared after four days in both 

 immune and non-immune rabbits, there being at no time any apparent 

 difference in the quantity of q^^ albumin present in these animals. 

 Hamburger (p. 1191) considers that this observation makes it all the 

 more difficult to explain the disappearance of the albuminuria in 

 immune animals, although this may possibly be due to immunity 

 having been acquired by the kidney cells. The probabilities are 

 that the reaction between the precipitin and precipitable substance 

 constitutes but one of several reactions which are taking place in the 

 body, as to the nature of which we are ignorant. As Rostoski, and 

 Michaelis, and Oppenheimer (1902, p. 363) state, all we know is that 

 precipitation does not appear to occur in corpore. 



By analogy with what takes place in vitro upon the mixture 

 of precipitin and precipitable substance, precipitation should take 

 place in the body of an animal whose seriun contains precipitin when 

 precipitable substance enters its circulation. If such a reaction took 

 place with anything like the rapidity with which it does in vitro, it 

 is needless to say that it would be fatal. to the animal, leading to the 

 formation of thrombi, etc. The remarkable thing is that the animal 

 remains well. Rostoski (1902, h, p. 40) thinks that the absence of 

 precipitation in corpore may be due to three causes, (a) the strongly 

 alkaline reaction of its blood, (6) the large amount of albumin contained 

 in its serum (about 7 7o), (c) and possibly to the presence of antipre- 

 cipitins. 



Michaelis and Oppenheimer (1902, p. 363) draw attention to the 

 possible significance of the enurnious leucocytosis observable in immune 

 animals upon the injection of fresh precipitable substance, and they 

 consider that the leucocytes may possibly take up the precipitum the 

 moment it is formed. This would be scarcely demonstrable. They 

 do not think the leucocytes would take up the foreign albumin as such, 

 but they might take it up after it has been acted upon by the precipitin 

 which circulates in the plasma. 



Hamburger (6, XI. 1902, p. 1191) believes that a combination is 

 effected in corpore, for the reason that the amount of precipitin 

 decreases after fresh egg-white injections. In support of the statement 



9-3 



