874 H. R. Seddon: 



standardisation of the test in the hands of different workers, so 

 that the interpretation and comparison of lesnlts may be possiljle 

 and accurate. 



a. — The use of whey and the value of ihc meihod. 



That the specific agglutinins of Bacillus ahortus may occur in 

 milk has been mentioned by MacFadyean anil Stoclcman, (1) in 

 the Appendix to Part 1 of the Departmental Committee's Report, 

 p. 28, where they say : " We also found that the milk of an animal 

 which had aborted possessed agglutinating i)roperties up to 1 in 

 25, but, owing to the opacity caused l)y the addition of milk to a 

 culture, milk is unsuitable for testing purposes." Whether this 

 product has been used at all in diagnosis I am not aware. 



It is obvious that if milk, or milk products, could be used it 

 would be advantageous, owing to the ease of securing specimens; 

 but, as milk, even diluted, is unsatisfactory on account of its physi- 

 cal properties, experiments were made Avith whey. The whey was 

 obtained by clotting milk with Lactic Acid, the technique being as 

 follows : — 



To 9 c.c. of milk, 1 c.c. of a 10% aqueous solution of lactic 

 acid is added and mixed. The coagulated milk is then filtered 

 through either cotton-wool and filter-paper, or filter-paper alone, 

 the latter method being usually applied. 



The whey is then diluted, one part to nine parts of carbolised 

 saline (Acid. Carbol. \'n\. 0.5, Sod. chlor. 0.85, water 100), to 

 form the basal dilution 1 in 10, and incubated over-niglit. Incu- 

 bation and subsequent filtration are found necessary, otherwise 

 there may be a deposit of albuminous material, which, though 

 unlike the typical deposit of agglutinated organisms, is not desir- 

 able, since it may lead to confusion in reading the results. 



With the diluted, incubated, and filtered whey, four tubes, each 

 receiving 0.6 c.c. of standard bacterial emulsion, ;ire put up. con- 

 taining the following amounts of the basal dilution of whey (1 in 

 10). 



rhey). 



