4 
Marine-Hospital Service. From time to time duplicates of tliis serum 
will be made to guard against deterioration or accident to the oidginal. | 
This standard serum is preserved in small tubes. Every two months | 
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 l)y the Secretaiy of the Treasuiy on recommendation of 
the Surgeon-General of the Public Health and Marine-Hospital Serv- 
ice. This license is issued only after a caref id inspection of the estab- 
lishmentj its methods of manufacture, and an examination of its prod- 
ucts for purity and potency at the ly^gienic laboratory of this Service. 
The strength of diphtheria antitoxin is expressed in units. As the 
question has often been asked, What is the unit for this country? it 
became the dut}^ of the Public Health and Marine-Hospital Service 
to establish and maintain a standard of measurement in order to bring 
about uniformity among American manufacturers. There is also the 
advantage of guaranteeing to ph 3 "sicians and patients using this won- 
derful specific reined}^ for diphtheria the fact that the}^ are employing 
a remedy of sufficient strength to protect or cure. Weak serums 
have been shown to be practicall}^ useless. 
The A^eiy unfavorable results obtained in England in 1895 in the 
handling of diphtheria with serum were due, according to the report 
of the Lancet Commission (Lancet, duly 19, 1896), in a great majority 
of cases to the use of serums too weak to produce therapeutic results. 
Experimental researches, for example, the veiy careful work of 
Madsen, in Copenhagen, 1896, showed that for therapeutic purposes 
weak serum is of veiy 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 therap}", as well as for the purposes of scientific investiga- 
tion, it is important to use an antitoxin whose value has been definitely 
ascertained. 
