130 APPLIED BACTERIOLOGY 



vein, and drawing off the required quantity of blood into 

 sterile glass bottles. The bottles containing the blood are 

 placed in an ice-chamber to allow the clot to separate, or 

 the clot may be more expeditiously removed by submitting 

 the blood to centrifugal treatment in a suitable machine. 

 The clear serum is then separated and preserved for use by 

 putting up in small sterile, stoppered bottles. Some makers 

 add a small quantity of an antiseptic, such as phenol, 

 camphor, etc., but this should be unnecessary with care- 

 fully prepared serum. One of the firms supplying this 

 article evaporate the serum to dryness in vacuo, and send 

 it out in the form of golden-yellow scales, which dissolve in 

 three or four parts of water. 



Louis Cobbett {Journal of Pathology and Bacteriology, 

 January, 1896) has arrived at the conclusion that the blood 

 serum of normal horses may possess a certain amount 

 of antitoxic power, and that there are two distinct 

 therapeutic agents present in the blood of immunised 

 horses. He also finds that there is a gradual diminution 

 of antitoxic power in the serum yielded by horses, even 

 though they continue to receive doses of toxins. He is 

 of opinion that the best method of obtaining antitoxic 

 serum is to begin by injecting the horse with a culture of 

 living bacilli. 



The preparation of a horse to give serum of very high 

 antitoxic value by the above method involves long treat- 

 ment, extending to six months or more. Dr. Cartwright 

 Wood has, however, recently devised a method for rapidly 

 producing diphtheria antitoxin, by which he claims that an 

 animal can be rendered immune towards large quantities of 

 diphtheria poison, and also that such animals can be made 

 to produce powerful diphtheria antitoxin. The distinctive 

 feature of the method consists in the use of the products 

 produced by the growth of the diphtheria bacillus in 



