180 EXPERIMENT STATION RECORD. 



The Stoke, Stewart, TroimiisddrlT, and l)(jane-Buckley methods of determin- 

 hig loiifocytes in milk are described and compareil. In 20 samples of market 

 milk these methods showed a. certain, althongh not a uniform relationship. 

 When one ran high the others usually also showed a high count. Streptococci 

 were found either on staining tlie sediment or on the agar plates in each of the 

 20 samples examined. 



In all samples taken in a careful uuuuu'r from a young cow in her first lacta- 

 tion period the leucocyte count and the percentage of sediment was very low, 

 considered with relation to the standard. No streptococci were found either 

 on examinaton of the sediment or on the agar plates. In the majority of sam- 

 ples from a cow having inflammation of the udder streiitococci were found 

 either in the sediment or on the agar plates. There seemed to be some relation 

 between the presence of the strejitococci and the number of leucocytes. 



The fore milk, middle milk, and stri])pings, both luiheated and heated to 70° 

 C, were studied, and 40 out of 42 samples examined showe<l a much larger 

 number of cells in the heated samples than in the unheated. A number of 

 samples were also examined at different temperatures in order to observe at 

 what point the change in the apparent leucocyte content occurred. 



" The most satisfactory results were obtained between 00° C. and 70°. 

 Tliere was an increase at SO, !)0. and 100°, but the results were not so uniform 

 and the examination was much more difficult to make on account of the coagu- 

 lated albumin, which interfered with the count. At the high temi)eratures the 

 leucocytes were moi-e or less disintegrated and could not be so easily differenti- 

 ated from foreign material, hence the count was rendered less reliable. 



" In pasteurized milk the leucocyte count is usually higher than in raw milk ; 

 therefore it was thought desirable to examine a series of four tubes from the 

 same sample. The first tube was unheated ; the second was heated to 70° ; 

 the third was heated and then cooled, and kept at 15° for twenty-four hours; 

 the fourth was heated, then cooled, kept at 1.5° for twenty-four hours, and then 

 heated again. ... In every instance after the milk was once heated the cooling 

 did not bring it back to its original conditicm, while the second heating to 70° C. 

 did not increase the count over the first heating. . . . 



" It appears that heating is as essential as any other part of the technique 

 in determining as nearly as possible the number of cellular elements in milk. 



" Since heating greatly increases the number in the count of the leucocytes, 

 it seems necessary that a higher leucocyte standard shall bo adopted in judging 

 milk." 



Bacterium lactis acidi and its sources, W. M. Estkn ( Connecticut Storrs 8ta, 

 Bill. .5.9, 2>I>- 0-27, //f/.s. .5). — This is a continuation of investigations previously 

 noted (E. S. R., 20, p. 178). It gives a brief resume of the economic importance 

 of B. lactis acidi, and reports investigations concerning the source of the 

 organism. 



Except in cases thought to be accidental, this species was not found in 

 different soils or hays, on leaves of trees and plants, or on grass. Of the grains 

 tested, cotton-seed meal, gluten bran, middlings, mixed feed, and corn meal, 

 only the corn meal contained a lactic-acid bacterium. Several parts of the 

 surface of the human body were tested, but no positive results were obtained 

 until the inside of the mouth gave evidence of a largo colonization. The bac- 

 teria were present in the feces of 11 out of 25 cows, but seemed to be somewhat 

 modified, having but little power to curdle milk. 



The organisms were found in abundance in the mouths and on the exterior 

 of nearly all the cows and in the feed troughs and mangers. In a few cases 

 the results were questionable, but it was thought that a repetition would give 

 positive results. Evidently the cow's mouth is the most abundant source of the 



