INTRODUCTION 3 



have been prepared against cynarase, fibrin ferment, pan- 

 creatic ferment, zymase, and urease. 1 



It therefore seems to be only a question of time when 

 we shall be able to prepare antibodies against ferments 

 and enzymes in general. 



An antibody to rennet is contained in the so-called 

 normal serum of the horse ; that is, horse blood freed of 

 fibrin by being shaken with small solid bodies such as glass 

 beads or pieces of iron wire, and separated from the red 

 blood corpuscles by centrifugation. (This was first shown 

 by Hammarsten and Roden. 2 ) In the same manner fresh 

 serum and even egg-white contain antibodies against many 

 other substances, as for instance against trypsin and 

 tetanolysin. By natural or normal blood serum is meant 

 that obtained from fresh animals that have not been inocu- 

 lated in any manner. If before the preparation of the 

 blood serum foreign bodies have been injected into the 

 veins of the animal, we obtain generally not normal serum 

 but serum containing an antibody, which is " specific " 

 to the injected body (i.e. immune-serum). 



In order to render this peculiar subject clearer I will 

 give a short review of the mode in which these antibodies 

 appear in the serum and how they afterwards disappear 

 from it. 



The next curve shows the concentration of cholera- 

 agglutinin in the blood of a goat, which had some time 

 before the experiment been immunised with cultures of 

 Vibrio cholera, so that the concentration of agglutinin in it 



1 Compare A. Schiitze : Zeitschr. f. Hygiene, 48 (1904). 



2 Roden: Upsala L'dkarefdrenings Forhandlingar, 22. 546 (1887); 

 Maly's Jahresbericht, 17. 160 (1887). 



