4 
Marine-Hospital Service. From time to time duplicates of this serum 
will be made to o-uard acfainst deterioration or accident to the oriodnal. 
This standard serum is preserved in small tubes. Every two mouths 
one of these tubes is opened, tested, and distributed to the licensed 
manufacturers and others who are working- in this line. 
The particular object of this standard is to insure the strength of 
antidiphtheritic serum sold in the United States by licensed manu- 
facturers. 
In accordance with the act of Congress approved July 1, 1902. no 
one is allowed to engage in interstate traffic in antitoxin without a 
license issued by the Secretary of the Treasury on recommendation of 
the Surg*eon-General of the Public Health and Marine-Hospital Serv- 
ice. This license is issued only after a careful inspection of the estab- 
lishment. its methods of manufacture, and an examination of its prod- 
ucts for purity and potency at the hygienic laboratory of this .Service. 
The strength of diphtheria antitoxin is expressed in units. As the 
question has often been asked. AYhat is the unit for this country ? it 
became the duty of the Public Health and Marine-Hospital Service 
to establish and maintain a standard of measurement in order to bring 
about uniformitv among American manufacturers. There is also the 
advantage of guaranteeing to physicians and patients using this won- 
derful specific remedy for diphtheria the fact that they are employing 
a remedy of sufficient strength to protect or cure. MTak serums 
have been shown to be practically useless. 
The verv unfavorable results obtained in England in 1895 in the 
handliog of diphtheria with serum were due. according to the report 
of the Lancet Commission (Lancet. July 19. 1896). in a great majority 
of cases to the use of serums too weak to produce therapeutic residts. 
Experimental researches, for example, the very careful work of 
Madsen, in Copenhagen. 1896. showed that for therapeutic purposes 
weak serum is of very little value. 
The fact need not be emphasized, as Ehrlich pointed out long ago, 
that for the whole question of the cure and prophylaxis of dipththeria 
by a serum therapy, as well as for the purposes of scientific investig*a- 
tion. it is important to use an antitoxin whose value has been definitely 
ascertained. , 
