12 
According to the former it is the physical movements of the ame- : 
bold cell searching for food which, a process known as phagocytosis, 
takes the bacteria into its protoplasm, forms a digestive vacuole ’ 
around it, and then excretes the enzymelike substances (cytase") use- j 
ful in protecting the organism against the soluble poison of the 
bacteria. 
According to Ehrlich the hungry protoplasm of any cell, with its ^ 
complicated molecule having side chains of various combining affini- i 
ties read}" to unite with suitable food molecules brought to it by the 
blood and body juices, lies at the foundation of his explanation of the ; 
chemical production of the antitoxin. It is strange that the same i 
combining affinity should exist between the protoplasm* of the cell and 
the proteid molecules that furnish it food as between the cell proto- . 
plasm and the toxines^ of the bacterial poisons. : 
In considering Ehrlich’s side-chain theory it is necessary to disre- ’ 
gard the microscopic structure of the cell and to think of the proto- i 
plasm as consisting of living molecules of extraordinary chemical ■ 
complexity. The molecule of protoplasm has a central “nucleus” ; 
with “side chains,” “lateral chains,” or “bonds" of varying combin- I 
ing capacities. These “side chains” serve to bind the molecule to • 
other molecules having proper combining affinities. 
This arrangement of molecules with side chains is a well-known 
occurrence in organic compounds. The benzol ring forms one of the 
best and simplest examples. 
H 
(OH) 
(OH) 
C 
C 
C 
/ \ 
/ \ 
^ / \ 
HC CH 
HC CH 
1 II 
HC C (OH) 
HC CH 
HC C (CII3) 
HC C (OH) 
\ / 
\ / 
S / 
C 
C 
c 
H 
II 
H 
Benzol CgHp, 
Metacresol CgH, (CTT) (OH) 
Pyrogallic acid (OH); 
(t Macrocytase, microcytase, philocytase. | 
I have made a distinction in this iailletin between “ toxine” and “ 
Some confusion arises in the literature for want of two words to re})i’esent two 
separate sul^stances. The diphtlieria poison contained in the toxic broth was hrst 
called “toxine,” usually “toxin.” It is now often spoken of as the “diphtheria ij 
poison.” This filtered broth, containing; a mmiVjer of poisonous substances, I have | 
called the toxine. | 
I have restricted the name “/o-rm” to the most important constituent of the | 
toxine. The toxin, as will be found later, is only one of several allied poisons found 'ji 
in the toxine. 
c Ehrlich: Die wertbemessung dea diphtherieheilserums und deren theoretische 
grundlagen. Klin, jahrb., Jena, v. 6 (2), 1897, pp. 299-326. 
