70 DEPARTMENT OF AGRICULTURE. 



discard any such somce of virus. A clear pleural fluid is ofteu very use- 

 ful for preservation, but i)erhai)s <;Teater reliance is to be placed on the 

 exudation of a i)ie('e of lung in tlu' first stage of the malady. The lung 

 is [)hu'ed on a tolerably ^vide strainer, or bits of wood, over a clean stone- 

 ware, glass, or porcelain dish or bowl; it is cut in various directions, and 

 a stout piece of cloth or flannel is placed over the whole to confine the 

 heat and prevent dust falling on the lung or liciuid.* It is better to place 

 the dish or bowl over a warm water or sand bath at 100°, so as to pre- 

 vent gelatinization. In a short time, according to the condition and 

 quantity of lung, a sufllcient quantity of clear yellow-colored .li<juid is 

 obtained. Sometimes blood accidentally tinges the material, and this is 

 not uecessaril}- a disadvantage. 



The old plan of keeping pieces of lung to inoculate with, and bot- 

 tling up anything and everything to secure a fetid compound, which 

 was kept for months, must be regarded as the most certain means to 

 insure accidents as the results of inoculation. 



Third. The preservation of the virus for periodic inoculations has 

 certaiulv been a desideratum. Had farmers and dairvmeu had the facil- 

 ities for procuring material which could be used with safety in their 

 stock, they would long since have tried a method that, even when badly 

 carried out, is beneficial to them. Dr. Sticker, of Cologne, has preserved 

 the virus in hermetically-closed tubes containing from one to two 

 drachms. One of these glasses is emptied into a small glass, and from one 

 to two parts of rain water added. This is not desirable. A plan has 

 occurred to me of utilizing the tubes referred to in Drs. Billings and 

 Cui'tis's report, which I am sure will meet the requirements of the ca.se. 

 Tubes about four inches in length, three-eighths of an inch in diameter, 

 antl tapering at either end, are sealed at one end in a blow-pipe flame, 

 and then heated throughout their length to redness. The operation is 

 concluded by closing the other end in the same way. The air in the 

 tube is rarefied, all germs of decay destroyed, and there is no difficulty 

 in further manipulations. When a proper ([uantity of liquid is obtained 

 one point ol the tube is passed into it, the tip broken off, ami the virus 

 is sucked in to fill the vacuum. A spirit lamp is held near the licjuid 

 and the point of the tube transferred from this to the flame. By the 

 aid of a blow-pipe the sealing is effected, and thus protected the virus 

 will keep for months. The test for discarding tubes thus prepared is a 

 microsco])ical one, and consists in the detection of bacteria or evidences 

 of putrefaction in the liquid. 



Fourth. The inoculation of cattle is most safely practiced on the tip 

 of the tail. All parts that .are loose, and from which any extensive 

 exudation may s]»read over the connective tissue beneath the skin, must 

 be avoided. The lips, dewlap, and root of the tail have proved dangerous 

 localities. AVhen the operation is properly and delicately i)erformed, 

 the tii» of the ear is said to be safe, but on the whole the end of the tail 

 is after long experience found to be the best. 



Dairymen have frequently resorted to the plan of making an incision 



