MIRACLES OF SCIENCE 



estimated at no less than three hundred and fifty mill- 

 ion dollars. This estimate was made by Dr. George 

 M. Kober, in a paper read before the White House 

 'Conference of Governors, in 1908. 



Though this inoculation against typhoid marks a 

 new and most important departure in medical science, 

 it must not be inferred that it constitutes an entirely 

 novel procedure. Jennerian vaccination agaist small- 

 pox, and Pasteur's celebrated inoculation -against 

 anthrax and against rabies are illustrations of im- 

 munization produced by the introduction of a virus 

 attenuated in strength or limited as to quantity. But 

 the novelty of Wright's experiments consists in the 

 fact that they were attended at all stages by careful 

 and systematic bacteriological observation (whereas 

 in the case of smallpox and rabies, the germ had not 

 yet been isolated) ; and in particular that the effects 

 of the inoculation were observed and tested by an en- 

 tirely new method. 



This new method is based on the observation of 

 the so-called opsonic index. Being briefly inter- 

 preted, this means a test of the quantity of anti-bodies 

 present in the blood as demonstrated by the rapidity 

 with which the white blood corpuscles are observed 

 to ingest disease germs with which they come in con- 

 tact. The more "opsonin" present, the more readily 

 and rapidly the swallowing of germs by the blood cor- 

 puscles goes on. Actual count of the number of germs 

 ingested, on the average, in a given time, gives the 

 microscopist information about the condition of the 

 patient's blood that could be gained in no other way. 

 Professor Wright and Dr. Douglas discovered this 



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