PROTECTIVE INOCULATIONS. 319 



Ion cultures for the preparation of mallein. The potatoes are to be 

 washed, before sterilization, in a five-per-cent bicarbonate of soda 

 solution, "until the wash-water remains clear." They are then 

 cooked for an hour and twenty minutes. After planting upon the 

 surface glanders bacilli from a previous culture they are placed in an 

 incubator at 36 to 36.5 C., with provision to prevent them from be- 

 coming dry. At the end of two weeks the growth is removed with a 

 platinum spatula and added to nine parts of water, in which it is well 

 mixed by rubbing. It is then allowed to stand for twenty-four hours, 

 after which it is sterilized for fifteen minutes at 110 0. (a lower tem- 

 perature would no doubt answer quite as well). After cooling it is 

 passed through a Chamberlain filter by means of a pressure of six 

 atmospheres. The filtrate is then carefully evaporated over a water- 

 bath to one-fourth its volume, and to this concentrated extract gly- 

 cerin is added in the proportion of one part to two. The mixture is 

 again sterilized in the autoclave at 110 C. When injected into 

 healthy horses in the dose of two cubic centimetres this mallein does 

 not cause an elevation of temperature exceeding 0.5 to 0.8. But 

 one cubic centimetre injected into a horse having glanders causes its 

 temperature to mount to 40 C., and at the point of inoculation a con- 

 siderable swelling is developed which lasts from four to six days 

 in healthy horses a swelling the size of a man's fist is developed at 

 the point of inoculation, which disappears within twenty -four hours. 

 In Pasteur's laboratory, according to Nocard (1892), mallein is 

 prepared as follows : The glanders bacillus is first made so virulent 

 by successive inoculations in susceptible animals that it will kill a 

 rabbit or a white mouse in a few hours. This virulent bacillus is cul- 

 tivated in glycerin-peptone-flesh-infusion (five per cent of glycerin and 

 five per cent of peptone). The cultures are kept in the incubating 

 oven for four weeks at a temperature of 31 C., and then sterilized in 

 the autoclave at 110 C. They are then filtered through paper and 

 evaporated, in vacuo, over sulphuric acid, at a low temperature, to one- 

 tenth of the original volume. The result is a syrup-like, dark-brown, 

 strong-smelling liquid, which is about one-half glycerin. This can 

 be preserved in a cool and dark place for a long time. When it is to 

 be used nine parts of a 0.5-per-cent solution of carbolic acid are 

 added to one part of the glycerin extract. The concentrated extract, 

 when injected into a healthy horse in the dose of one-half to one cubic 

 centimetre, causes a local swelling which disappears after two or three 

 days. The temperature of the body is elevated from 1.5 to 2 C. as 

 a result of the injection, and there are chilliness, loss of appetite, and 

 debility. When the diluted mallein is injected in healthy animals in 



