RABIES 299 



left at a tcmporatiiro of 37° until they become hardened^ then the sec- 

 tions are transferred to liquefied paraffine and left there for an hour at a 

 temperature of 60°, then the sections are put in cold water to which a 

 small quantity of gum aral3ic is added and put in a stone and the paraffine 

 carried off, then the sections are colored by means of Mann's process, 

 which is to put the sections for one-half to four minutes in a coloring 

 solution consisting of 35 c.c. of 1 per cent, aqueous solution of methylene 

 blue and 35 c.c. of 1 per cent, aqueous solution of eosin and 100 c.c. 

 of distilled water. The sections are rinsed with water and then put 

 in absolute alcohol for 15 to 20 seconds, to which has been added 

 some caustic soda (to 30 c.c. of alcohol add 5 droi>? of 1 per cent, 

 solution of absolute alcohol). The sections are again put in alxsolute 

 alcohol for a few moments and then washed in water for a minute; the 

 sections are now put in water slightly acidulated with acetic acid, 

 drained and sealed with canada balsam. 



The following procedure has been the method employed for the 

 rapid diagnosis of rabies in the laboratory of the Veterinary school of 

 the University of Pennsylvania for several years: As soon as the 

 animal's head arrives at the laboratory the entire brain and the 

 plexiform ganglia, with the adjacent sympathetic ganglia are removed. 

 A portion of the cerebellum is placed in sterile glycerine, in which the 

 })rain tissue may be preserved and retain the virus for many weeks. 

 These glycerine-immersed specimens are only referred to for the animal 

 inoculation test when the microscopic examination is unsatisfactory. 

 Aside from preventing decomposition, the glycerine will also destroy 

 bacteria and check decomposition of the specimens. From the fresh 

 brain tissue, smears are usually made from the hippocampus major and 

 cerebellum. A piece 1 mm. thick and several millimetres in diameter 

 cut from the freshly exposed surface, after an incision is made through 

 the hippocampus major at right angles to its length, or of the cerebellum 

 in which an incision has been at right angles to the convolutions, is 

 placed upon a slide near one end. Instead of using a cover-slip, another 

 slide is placed over the small piece of tissue and gentle pressure is applied 

 and the opposite ends of the slides are moved toward one another. The 

 smears are then placed in alisolute alcohol for two to five minutes, 

 whereupon the alcohol is allowed to evaporate and the smears then stained. 

 The stain as recommended by Van Giesen is used. 



Loeffler's alkaline methylene blue, 1 part. 



Distilled water, 1 part. 



Saturated alcoholic solution of fuchsin added in drops 

 until the mixture has a purple tinge, or initil a metallic 

 scum is seen on the surface. 



The mixture kept at a low temperature can be used for an unlimited 



