Specificity of Reactions 157 



lactoscrum for cow's milk produced a thick flocculent precipitate in cow 

 milk dilutions within a few minutes, whereas it left human and donkey 

 milk dilutions unaffected. 



The specific character of the reaction was dwelt upon by Wassermann 

 and Schiitze, who stated that no reaction took place, for instance 

 between the lactoserum for cow's milk and goat's milk, and vice versa. 

 This result may have been due to their using weak lactosera, for the 

 results of other workers have been different with the milks of animals 

 so closely related. Thus Moro (31, X. 1901) found the lactoserum for 

 cow's milk to precipitate goat's milk. This is in perfect agreement 

 with what I found with regard to the antiscra for the corresponding 

 bloods, and is also in accordance with the observations of Ehrlich and 

 Morgenroth, who found that injections of the blood corpuscles of the 

 ox into experimental animals led to the formation of an haemolysin 

 which acted not only on the corpuscles of the ox, but also on those 

 of the goat. 



The question of specificity was next studied by Gengou (25, X. 1902, 

 p. 749) with lactosera from rabbits treated with cow's milk. He states 

 that the reactions which took place in the milks of the cow, sheep and 

 goat were indistinguishable when he made the following tests. He 

 prepared two tubes containing : 



I. Milk (of cow, goat, or sheep, etc.) II. Milk (as in I.) 



Lactoserum (heated to 56 C.) Normal rabbit serum (heated to 56 C.) 



Normal rabbit serum, fresh Normal rabbit serum, fresh 



He found that the complement or " alexine " (of the fresh normal rabbit 

 serum) was absorbed in I. and not in II., throughout the series, when a 

 lactoserum was added to its homologous milk. It was in this that 

 the three milks above named were indistinguishable. The immune 

 substance acted to a lesser extent upon human and mare's milk. 

 The lactoserum, he adds (p. 754), did not act upon ox serum (see 

 contrary below). Schiitze (6, XI. 1902, p. 804) found that a powerful 

 isoprecipitin (see p. 148) for goat's milk did not produce a reaction 

 in human milk dilution even after a considerable time, though he does 

 not state how long. 



Milk boiled for half-an-hour, according to Schiitze (loc. cit.) still 

 gives a slight reaction upon the addition of antiserum. Moro 

 (31, X. 1901, p. 1076) obtained an antiserum from rabbits treated 

 with milk which had been boiled for half-an-hour or upwards. He 

 found that milk which had been boiled for 30 minutes reacted im- 



