THERAPEUTIC IMMUNIZATION IN MAN 493 



paralyzed it is killed by chloroform and the cord is removed best by 

 the method of Oschida. 100 The rabbit is nailed to a board, back up- 

 permost, and washed with a weak antiseptic ; a longitudinal incision 

 is then made along the backbone from the occiput to the lumbar 

 region, and the vertebral column laid bare. 



After searing the tissues around the back of the head the spine is 

 cut across just behind the occiput, and again in the same way just 

 above the sacrum. The neck and lumbar regions are dissected loose 

 from the skin and gauze is inserted under it to avoid contamination. 

 The assistant grasps the end of the spinal cord as it appears in the 

 cervical region and pulls on it very slightly while the operator with 

 a glass rod or a piece of wire pushes against it from below. If this 

 is carefully done the spinal nerves are torn and the cord can be 

 gradually pulled out of place. This procedure is by far the best, 

 although it requires a certain amount of practice. 



The cords so removed are hung up by a thread in bottles contain- 

 ing sticks of caustic potash and exposed in a dark place to 22 to 23 

 C. Under these conditions of drying and temperature the virus is 

 gradually attenuated until at the end of 13 days or more the viru- 

 lence is practically nil. If removed from the drying bottles at any 

 time during the process and kept in a refrigerator in sterile glycerin 

 the virulence, whatever it may be at the time of placing into the 

 glycerin, remains fairly constant for long periods. When any of 

 this material is used for treatment little pieces of the cord % cm - i n 

 length are cut off and emulsified in 2.5 c. c. of salt solution, and this 

 emulsion is used for injection. 101 



When patients are to be treated the principle of the treatment is 

 to inoculate them first with cords that have been dried for consider- 

 able periods, gradually proceeding toward those that have been dried 

 for less prolonged times and are therefore more virulent. The treat- 

 ment is varied in the individual case according to the severity of the 

 injury. Formerly treatment was begun with cords dried as long as 

 16 days. More recently it has been found that cords dried for longer 

 than 8 days are practically non-virulent and correspondingly lack 

 in antigenic value. They are no longer employed, therefore, since 

 their use is regarded as a waste of time. The tables on p. 494, taken 

 from Stimson's article in Bulletin 65 of the Hygienic Laboratory of 

 the U. S. Public Health Service, give the standard methods of treat- 

 ment as recommended by the United States Public Health Service. 



This is the standard treatment used almost everywhere in the 



100 Osehida. Centralbl f. Bakt., Vol. 29, 1901. 



101 In our description of the methods of drying rabies, for the sake of 

 adhering to a standard, we follow closely the directions laid down by A. M. 

 Stimson, in the U. S. P. H. S. Bull 65, 1910. There are various modifica- 

 tions used in different countries, in many cases unimportant, and it seems 

 well to adhere to the U. S. regulations as a standard for this country. 



