230 SUSCEPTIBILITY AND IMMUNITY. 



mann have published the results of their interesting experiments 

 with a bouillon made from the thymus gland of the calf. It was 

 found that the tetanus bacillus cultivated in this bouillon did not 

 form spores and had comparatively little virulence. Mice or rabbits 

 inoculated with it in small doses 0.001 to 0.2 cubic centimetre for 

 a mouse proved to be subsequently immune. And the blood serum 

 of an immune rabbit injected into the peritoneal cavity of a mouse 

 0. 1 to 0. 5 cubic centimetre was found to give it immunity from 

 the pathogenic action of a virulent culture of the tetanus bacillus. 

 Similar results were obtained with several other pathogenic bacteria 

 cultivated in the thymus bouillon spirillum of cholera, bacillus of 

 diphtheria, typhoid bacillus. We give here the directions for pre- 

 paring the thymus bouillon as used by the authors named : 



Two or three thymus glands are chopped into small pieces immediately 

 after they are taken from the animal. An equal part of distilled water is 

 added to the mass and stirred for some time ; it is then placed in an ice chest 

 for twelve hours. The juices are now expressed through gauze by means of 

 a flesh press. A clouded, slimy fluid is obtained, which constitutes a stock 

 solution. This is diluted with water, and a certain quantity of carbonate of 

 soda is added to the solution before sterilization. By this means coagulation 

 and precipitation of the active substance from the thymus gland are avoided. 

 The exact amount of water and of sodium carbonate required to prevent pre- 

 cipitation must be determined by experiment, as it differs for different glands. 

 Usually an equal portion of water and sufficient soda solution to turn litmus 

 paper feebly blue will give the desired result. The liquid is now heated in 

 a large flask, which is left for fifteen minutes in the steam sterilizer. The 

 liquid is allowed to cool and then filtered through fine linen to remove any 

 suspended coagula ; the filtrate has a milky opalescence. It is now placed 

 in test tubes and again sterilized. The active principle is precipitated by the 

 addition of a few drops of acetic acid . 



Additional facts bearing upon this important question have been 

 developed by the experiments of Ogata and Jasuhara, which show 

 that the anthrax bacillus, when cultivated in the blood of an immune 

 animal (rat, dog, or frog), becomes attenuated as to its pathogenic 

 power, and that such cultures injected into a susceptible animal 

 give rise to a mild attack followed by immunity. Moreover, the in- 

 jection of a small amount one drop of blood from a frog or a dog 

 into a mouse, made before or after inoculating it with a virulent cul- 

 ture of the anthrax bacillus, was found to protect the animal from a 

 fatal attack, and, after its recovery from the mild attack resulting 

 from the injection, it proved to be immune. The protective influence 

 was exercised when the blood was injected as long as seventy-two 

 hours before the inoculation, or five hours after ; and it was not lost 

 when the blood was kept for weeks in a cool place. But subjecting 

 it to a temperature of 45 C. for an hour completely destroyed its 

 power to protect inoculated mice from a fatal attack of anthrax. 



Similar results have been reported by Behring and Kitasato in 



