DIPHTHERIA. 227 



dose does not exceed I cu. cm. The examination with re- 

 gard to the qualities of the test-toxins should be continued. 

 VII. The test-toxins, if liquid, are to be examined 

 monthly with regard to their sterility by means of culture- 

 methods. 



VIII. The test-poison is to be redetermined at intervals 

 of six weeks by means of the test-dose of serum, the test- 

 dose and the net-valuation being estimated anew. If, on 

 reexamination, any considerable deviation in the test-dose 

 should be detected, the toxin must be considered to be in 

 process of decomposition, and it should be replaced by fresh 

 toxin. 



IX. The manufacturers are to be informed that the 

 test-toxin in small amounts decomposes readily, and that 

 even brief exposure to light may induce considerable at- 

 tenuation. It is therefore to be recommended that a new 

 supply of toxin be obtained from the laboratory every three 

 weeks.* 



Diphtheria-antitoxin is prepared in Germany in four 

 establishments namely, the Hochst Works, the Factory 

 of Schering, in-Berlin, the Pasteur Institute in Stuttgart, and 

 the Factory of Sthamer, Noack & Company in Hamburg. 



The Hochst Works manufacture the following prepara- 

 tions : 



ANTITOXIN OF 250 TIMES THE NORMAL STRENGTH. 

 Number o, yellow, . .0.8 cu. cm. contain 200 immunity-units. 

 Number I, green, . . 2.4 " " 600 " 



Number 2, white, . . 4 " " 1,000 " 



Number 3, red, ... 6 " " 1,500 " 



* Dr. Jos. McFarland and Dr. Chas. T. McClintock, to whom these regula- 

 tions were submitted, kindly describe, as follows, the method of testing pur- 

 sued by the largest manufacturers of diphtheria-antitoxin in the United States : 



" In order to secure uniformity in the toxin the same culture of the diph- 

 theria-bacillus is always employed. This is grown for seven days at 37 C. 

 (98.6 F.) in an accurately prepared alkaline two per cent, peptone-bouillon. 

 The same degree of alkalinity is always secured (phenolphthalein being used as 

 the indicator in titration). After addition of 0.4 per cent, trikresol, this 

 toxic bouillon is filtered through unglazed porcelain and stored in a dark, cold 

 place. The amount of this toxin that will kill a guinea-pig weighing 250 

 grams on or before the sixth day is considered the minimum fatal dose. 

 Should this toxin deteriorate ten per cent, from its original strength, it must be 

 discarded. 



" In testing antitoxin, a series of guinea-pigs, weighing from 240 to 270 

 grams, are injected with ten times the minimum fatal dose of toxin previously 

 mixed with varying amounts of antitoxin. Those pigs are considered protected 

 that do not die or lose more than 20 per cent, of their original weight in seven 

 days." A. A. E. 



