iPfemCiPLES OF VETERINARY SURGERY 493 



MICROSCOPIC EXAMINATION, even without stain- 

 ing, permits the determination of their nature with great ac- 

 curacy. Staining with picro-carmin gives the most beautiful 

 preparations. The yellow stain becomes fixed on the center 

 of the parasite, while the carmine stains the periphery, the 

 gelatinous covering and the lymphatic elements, which the 

 latter contains. To simplify the description, two zones are 

 distinguished in the tufts of the parasite. The central zone 

 is composed of fibrillary matting whose filaments are spiral 

 and ramified and they radiate toward the periphery. (Fig. 

 51). The peripheric zone is constituted of club-shaped ele- 

 ments. These pear-shaped enlargements are characteristic; 

 they are yellow, very refractive, homogeneous, four to 

 twelve microns long and four microns wide. They are sim- 

 ple or bifurcated and sometimes vary in length. Some of 

 them extend perceptibly beyond the limits of the tuft. Num- 

 erous hypotheses have been advanced on the constitution, 

 the nature and the function of these enlargements. Bostrom 

 thought he had found a filament in their axis that is continu- 

 ous with the filaments of the central zone. Harz, Carmel 

 and Babes at one time maintained that they were organs of 

 generation. It is now established that they are naught but 

 involute arrangements. 



METHOD OF STAINING. — Staining is necessary in or- 

 der to properly study the details of the structure of the para- 

 site. The actinomyces either does not take Gram's stain well 

 or else is badly stained by that method. Picro-carmine, on 

 the contrary, gives a good preparation. Lemiere and Beene 

 approve the following method : Place a little of the pus in a 

 watch glass and wash well with ether and allow it to bathe 

 for some time in a recently prepared concentrated solution 

 of caustic soda or potash, and then from ten to fifteen min- 

 utes in a 5 per cent aqueous solution of eosin. The specimen 

 is then washed in a concentrated solution of sodium or potas- 

 sium acetate, mounted in the same solution and imbeddecj 



