Microscopic Examination. 223 



The presence of epithelial nests from the cistern suggests a 

 catarrh of the cistern. 



An increased number of leucocytes and colostral cells indicates 

 an irritation of the parenchyma. The causes of the irritations 

 are often manifested by the presence of diplococci in phagocytes 

 or isolated diplococci and frequently atypical short forms, or the 

 typical animal forms of the Streptococcus longus or S. brevis are 

 recognized. 



Even atypical forms of diplococci and streptococci, when pres- 

 ent in such forms in milk only a few hours old, are an indication of 

 streptococcic mastitis (care must be exercised in the absence of 

 experience and if the evidence is to be used in court). 



In pyobacillosis the typical, short, slender bacilli are found 

 which simulate in their morphology the bacilli which frequently 

 cover the horny cells of the outside skin of the teats. 



In samples from individual cows, the microscopical examina- 

 tion may establish the diagnosis of "tuberculosis of the udder," 

 when the specific organisms are found enclosed in leucocytes or 

 curds. The staining is carried out with hot carbol-fuchsin solution 

 (1 part fuchsin to 10 parts of absolute alcohol, and 90 parts of a 

 5% carbolic acid solution). By decolorizing with 33% aqueous 

 nitric acid and subsequent washing with alcohol the non-acid fast 

 rods and the body cells are decolorized. The decolorized elements 

 may be given a blue contrast stain, against the red tubercle bacilli 

 by subsequent staining of the preparation with aqueous methylene 

 blue or methylene blue anilin water. 



In order to avoid the dragging of too many tubercle bacilli 

 into the cream by the cells and fat globules, for the microscopical 

 examinations, the milk should be first homogenized. The following 

 methods are the simplest : 



a. Knut Arnell recommends mixing 25 c. c. of milk with 2 c. c. 

 of concentrated ammonia and 100 c. c. of a mixture of equal parts 

 of ether and petroleum ether in a sedimentation cylinder, which 

 runs to a point at the bottom and at its lower part is supplied with 

 a stopcock. This is frequently shaken and then allowed to stand 

 for the separation. The ammonia-casein solution is then drawn 

 off, the remaining content is centrifugalized and the sediment 

 examined. 



b. Thorner recommends mixing 20 c. c. of milk with 1 c. c. of 

 50% potassium hydrate. This is heated in boiling water until in 

 complete solution and then centrifugalized. 



c. Biedert recommends adding 10 c. c. of milk to 1000 c. c. of 

 water containing 4 to 8 drops of sodium hydrate solution. This 

 is shaken, boiled and then set away for sedimentation. 



If after staining, the slender rods which remain red are pres- 

 ent only in small numbers, or if the sediment shows no cells which 

 indicate an inflammation of the udder, or if the examined milk 

 proves to be a dirty market milk, then the diagnosis must be estab- 



