156 Tests with Precipitins 



II. ZOOPRECIPITINS. 



I. Lactosera. 



The term "lactosera" was applied by Bordet (in. 1899, pp. 240 

 241), who discovered them, to antisera which precipitated milk casein. 

 Having partially sterilized milk at a temperature of 65 C. he injected 

 it intraperitoneally into rabbits at stated intervals. After a time he 

 bled the rabbits, and found their serum to possess the property of 

 causing precipitation in the milk with which the animals had been 

 treated. He performed the test by placing about 3 c.c. each of the 

 antiserum and of normal serum in tubes, to which he subsequently 

 added 6 15 drops of the milk. Whereas the mixture with normal 

 serum retained its opaque white appearance, the mixture with anti- 

 serum soon underwent a change ; fine granules appeared, and these 

 rapidly growing in size led to the formation of flocculent masses. Soon 

 the fluid became limpid above, the flocculi sinking to the bottom. This 

 was best observed in milk which had been deprived of an excess of fat 

 by being passed two or three times through filter-paper. When milk rich 

 in fat is used, the flocculi are carried upward by the fat globules. 

 In studying the reaction, it is therefore best to first filter tie milk. 

 The supernatant fluid remains clear, but may at times again show 

 a cloud upon the addition of fresh antiserum. 



Fich (ii. 1900, cited by Schiitze, 29, I. 1901, p. 7, footnote) soon 

 afterwards found that an emulsion of udder-cells, as well as milk, gave 

 rise to antisera which precipitated milk, when rabbits were treated 

 with these substances. The observation of Bordet has been since 

 amply confirmed by a number of investigators. The first of these to 

 suggest a practical application of the method in the differentiation 

 of milks were Wassermann and Schiitze (2, vii. 1900 and 29, I. 1901), 

 who treated rabbits with three different milks, namely those of the 

 cow, goat, and human subject. They claimed that these milks could 

 be distinguished from one another, the corresponding lactoserum acting 

 only upon its homologous milk. Their method of treating rabbits will 

 be found described under Methods (p. 53). Schutze (29, I. 1901, p. 5) 

 subsequently described their investigations in detail, and drew attention 

 to the possibility of using the lactosera in the examination for milk 

 adulteration. 



Uhlenhuth (G, xn. 1902), in testing with lactosera, adds 5 c.c. of 

 antiserum to 3 c.c. of a 1 : 60 milk dilution in salt solution. In his tests, 



