34 
Transactions Texas Academy of Science. — 1907. 
munizing the living organism against injury by the action of ferments 
that are normal to the living organism, and, indeed, are necessary to 
the normal performances of its functions; and against injury by the 
action of pathogens — disease-producing “germs” of infectious diseases. 
Professor Wells, of the University of Chicago, “Chemical Pathology,” 
1907, says, “Injection of enzymes into animals leads to the appearance 
of substances in the serum of the animals that antagonize the enzymes. 
The principles involved are quite the same as in the immunization of 
animals against bacterial toxin, or against foreign proteids.” “It seems 
highly probable that the resistance of the body tissues to digestion by 
their own enzymes and by the enzymes of one another depends in some 
way upon the presence of anti-enzymes in the cells and tissue fluids.” 
“Weinland has demonstrated that certain intestinal worms contain a 
strong anti-trypsin, to which he attributes their ability to live bathed 
in pancreatic juice without being digested. Similar properties have 
been ascribed by other observers to the cells of the mucosa of the stomach 
and the intestines.” 
The anti-enzymic property of the blood serum, acquired by inocu- 
lations of enzymes into the animals, is highly specific (v. Esler). 
“This fact permits us to distinguish between enzymes of apparently 
similar nature, but of different origin.” Artificial immune serum has 
been obtained against trypsin, pepsin, lipase, emulsin and fibrin fer- 
ment. 
ACQUIRED IMMUNITY. 
It is a. matter of common observation that a single attack of an in- 
fectious disease will, in many instances, temporarily or permanently 
immunize the patient against a recurrence of the disease. It is also 
generally known that vaccinations with a modified virus of the disease 
will immunize against smallpox and hydrophobia. But it is less gen- 
erally known that specific immunity against a great number of different 
kinds of infectious diseases may be acquired by repeated inoculations 
of small, then gradually increasing, doses of modified specific virus 
(toxins and pathogens) of the disease, and when these apparently dif- 
ferent means of inducing acquired immunity are analyzed that they all 
lead to the same end — the production of specific antibodies in the blood 
serum of the animal treated. 
There yet remains an important phenomenon of immunity that 
strongly confirms my contention, that the underlying causes of fermen- 
tation, infection, and immunity, are essentially the same. I refer to 
the fact that neither inoculated ferments nor pathogens “take,” except 
in animals that are not immune to these bodies. All are acquainted 
with the fact that vaccination against smallpox will not “take” in im- 
