392 
OLOF SCHWARZKOPF. 
the blood serum of an animal, rendered artificially immune 
against certain infectious diseases, if injected into another 
animal will protect the same against such disease or even cure 
him after infection.” The weak point of this new theory is 
our lack of understanding of the nature of “ immunity,” inas¬ 
much as there are several theories, notably those of Pasteur, 
Metschinkaff, Buchner, Behring, Roux and others. Each 
opposes the othei*, none fully explains his phenomena. We 
know, however, by empirical observation that certain animals, 
or classes of animals—are protected by nature—are “ naturally 
immune ’ against particular diseases, which are fatal to others. 
We also know that a previous sickness of certain diseases of i 
men and animals, such as scarlet fever, small-pox, yellow fever, 
influenza in horses, and many others, usually produce an 
“ acquired immunity ,” at least for a variable length of time, 
against another attack of the same disease. Moreover, we 
know that we can render animals “ artificially immune” 
against some infectious diseases by protective inoculation. 
Lately, we seem to have reached the point when “ curative 
immunity” can be produced in time to counteract the infec¬ 
tion and ward off the fatal toxic effects of certain germ 
diseases by the application of antitoxines. It is true that this 
new therapeutic applies at present only to a few diseases, 
diphtheria, tetanus and a few forms of septicasmia, such as 
puerperal fever of women, but it is no conjecture to conclude 
that others will be added in proportion as our knowledge of 
the pathogenic germ life becomes clearer and our laboratory 
methods improve in practicability and certainty of results. 
The production of the various antitoxines is preceded by 
the preparation of their toxins in the bacteriological labor¬ 
atory. This has been already described in our professional 
journals, and only for a better understanding of this paper I 
wish to recall to you the virulent bacilli of diphtheria and of 
tetanus, and the streptococcus of septic diseases are obtained 
from patients suffering from these diseases and cultivated on 
bouillon in large flasks in an incubator for several weeks, when 
they are filtered through a Chamberland filter, whereby the 
germs remain outside the filter, the filtrate being the original 
