14 
Fig. Ic. — The first stage of 
antitoxin formation; a 
fo.rwimolecule anchored, 
to a receptor. 
In 
required three times as much; that is, 0.009 c. c. to kill' a o’uinea pig. 
Nevertheless, the combining power of the toxine for antitoxin remained 
the same. 
Toxoids are altered toxins. They consist of the 
toxic molecule in which the toxophore group has 
been destro^^ed, leaving onl}- the haptophore or 
combining group, Avhich while able to satisfy- the 
combining affinities of the antitoxin is no longer 
able to poison the protoplasm of the cell. 
The diphtheria bacillus, during the process of its 
growth and multiplication in the body or in an 
artificial culture medium, produces several poisons, 
one of which is known as the diphtheria toxin. As above stated, the 
dq^htheria toxin consists of a toxophore and haptophore group, 
the l)od}" the latter unites cheniicall}" with the 
receptors of the cells. When this takes place 
one of two consequences may result: Either (1) 
the cell is so severely poisoned that it dies, or 
(2) the living molecule of protoplasm is stimu- 
lated so as to excite a defensive action b}" the 
reproduction of the receptors. Continued stim- 
ulation produced by the periodical injection of 
toxine results in an over production of recep- 
tors which finall}’ loosen and float free in the 
blood serum and bod}' juices. 
Antitoxin consists of these free receptors 
floating in the blood serum. If now we introduce a liquid containing 
the toxin into the blood, it is immediateh' neutralized by combin- 
ing with the free receptors through its hapto- 
phore group. All the combining affinities of 
the toxin are thus satisfied or saturated, so that 
the toxin is no longer able to unite with the 
receptors still attached to the cell, and this 
poison is thus rendered harmless. 
It is of the greatest practical importance to 
know from what organs or tissues the receptors 
derive their origin. 
It is b}' no means a necessary corollaiy of 
the side chain theoiy, as is often supposed, 
that the receptors are found only in those organs upon Avhich the 
poisonous eflects of a toxine are particularly manifested. On the 
contrary, Ehrlich and Morgenroth'^ believe that receptors capable of 
«Erhlich, P., & Morgenroth, J.: Wirkmig und entstehung der aktiven stoffe im 
serum nach der seitenkettentheorie. Haiidbuch der pathogen mikroorganismen, 
W. Kolle and A. Wassermann, Jena, 1904. 
Fig. Id.— The second stage; 
continued stimulation causes 
a reproduction of receptors. 
Fig. le.— Third stage; the re- 
ceptors beginning to leave 
the cell. 
