IMMUNITY AND ANAPHYLAXIS 187 



in salt solution, of which dilutions are made, and injections 

 made in reverse order of dilutions. Fewer accompanying 

 symptoms (as erythema at the point of injection, backache, 

 muscular pains, and occasionally temporary paralysis) 

 are noted, and this result is attributed to the less amount 

 of nerve tissue injected. 



By cultivation in a medium containing antiseptics in 

 a dilute state ; e.g., in presence of carbolic acid 1-600, or 

 potassium bichromate 1-5000, or sulphuric acid 1-200. 



By addition of weak antiseptic solutions to virulent 

 broth-cultures preparatory to their injection, as advised 

 by Behring for immunization of horses to diphtheria and 

 tetanus. The antiseptic advised is iodine terchloride, 

 IC1 3 , in strengths varying from 0*05 per cent to 0-4 per- 

 cent. Lugol's solution of iodine is also used. 



2. With Dead Bacteria. This method is simpler and 

 safer, and in many cases confers the same degree of 

 immunity, which is chiefly antibacterial. It is also 

 used preliminarily to injection of living cultures, in the 

 active immunization of animals. In the human being, 

 it is used for cholera, plague, typhoid, and in the treat- 

 ment by " vaccines " generally, as for staphylococcus 

 infection, etc. 



3. With Bacterial Cell Substances. This method is a 

 modification of that with dead bacteria. Instead of 

 injecting the culture heated to 65 C., or some such tempera- 

 ture, to kill the bacteria, the culture is subjected to various 

 processes as in the preparation of Koch's original tuberculin. 

 This is not purely bacterial cell substances, but is inter- 

 mediate between the simply heated culture and tuberculin- 

 R, which is an emulsion of the bodies of bacilli from which 

 all the soluble substances have been extracted by grinding 

 and treatment with distilled water (tuberculin-O). Hahn. 

 following Buchner, has used mechanical pulverization of 

 bacilli mixed with infusorial earth and quartz sand, and 

 subjected to 300 to 500 atmospheres' pressure by hydraulic 

 means, and has so obtained what he caUs the cell-juices 

 or bacterial plasmins, which he has used for immunization. 

 '' Cholera plasmin " and " typhoid plasmin " have both 

 proved effective jn immunizing guinea-pigs against intra- 

 peritoneal infection with ten times the fatal dose of virulent 



