RABIES 185 



which is opened and closed by pushing a button. It is passed through 

 the skin closed, then opened, the thread inserted, when it is again 

 closed and withdrawn. Of course, all the materials and instruments 

 have been sterilized, and during the operation are placed in a pan 

 of 3 per cent, carbolic acid. The rabbit is then placed in a box prop- 

 erly labelled. Wire cages are generally used, but if the floor be of 

 asphalt or of cement, a box without a bottom, having a wire grating for 

 a lid, with a bed of sawdust or straw, is more convenient to keep clean. 



"In an institute like the one at Baltimore, where approximately 

 120 cases are treated annually, two animals are daily inoculated, 

 the material for this purpose being obtained from the medulla of 

 those animals which have died of rabies during the day or the night 

 preceding. To this end a piece from the floor of the fourth ventricle, 

 measuring about 2 cm., in length is rubbed up in 1 c.c. of bouillon, 

 and of this emulsion, as I have just stated, three or four drops are 

 injected beneath the dura. 



"As I have mentioned before, rabbits that have been inoculated 

 with virus fixe develop rabies after an incubation period of from 

 six to eight days (the shortest period being usually only reached 

 after ninety passages), and then die almost four days later, viz., 

 after ten to twelve days following the inoculation. The dead 

 animals, as soon after death as possible, are sprayed with lysol or 

 bichloride and stripped of their fur, when the cord and brain are 

 removed under aseptic precautions. The cord is severed just below 

 the medulla and divided into two equal pieces, which are suspended 

 by sterilized silk threads in a sterile glass jar (aspiration or irrigation 

 bottles, 1 liter capacity), the bottom of which has been covered 

 about 2 cm. deep with flake caustic potash. The threads are held 

 in position by the cotton stopper and are allowed to hang outside. 

 The medulla is kept in a sterile dish and is used to continue the series 

 of inoculations, as indicated above. The jars are labelled with the 

 date, the number of the passage, and the number of the animal 

 passage. A post mortem finally is performed and any cord rejected 

 in which the animal is found diseased, or in which bacteriological 

 examination of the cord has shown the presence of pyogenic organ- 

 isms. 1 The jars are then kept in the cord room (occupying about 

 12 to 15 square feet) at a temperature of from 20 to 25 C. 



1 To this end a small piece is snipped off after twenty-four hours, dropped 

 into bouillon, and this incubated until the next day. 



