410 Dr. J. Mellanby. [June 3, 
Antitoxic Percentage of | Antitoxic Percentage of 
Days. value. solids in nae =e value. solids in serum. 
Horse A. Horse B. 
0 0 8°93 O 0 7°78 
60 225 -—— 97 350 9°02 
104 500 10°91 ' 148 1000 10 °54 
146 675 11°98 222 450 9°54 
190 575 12°10 266 250 10°6 
235 800 11°85 313 500 10 °4 
254 450 9°88 305 363 10°3 
302 700 11°53 395 250 10°1 
348 700 11°52 443 200 10 ‘77 
397 800 12°11 506 200 10°76 
460 575 12:0 
496 900 121 Horse C. 
533 500 1°76 (6) 0 8 °2 
574 800 10°75 5A 250 8-95 
624. 250 11°18 99 660 9°6 
700 333 10°81 143 333 9 -04 
750 363 10 °85 192 363 9°43 
810 250 11°88 241 571 9°65 
292 400 9°8 
341 500 9 °4 
decline of the antitoxin producing power implies the exhaustion of that 
mechanism by means of which antitoxin is produced. That this is not 
reflected in the amount of solid in the serum depends upon the fact that the 
exhaustion of this special mechanism does not imply a corresponding etfect 
on the general nutrition of the tissues. 
EHRLICH’S THEORY OF ANTITOXIN PRODUCTION. 
The salient point in the production of diphtheria antitoxin is that toxin 
in increasing doses is injected under the skin of a suitable animal, and, after 
a variable time, antitoxin appears in the blood. 
The explanation of these phenomena which has been most widely accepted’ 
is that of Ehrlich. This theory may be stated in general terms as follows :— 
The toxin combines with the side chain of a cell and so upsets the 
equilibrium of that cell. By virtue of its protective mechanism the cell 
manufactures a series of new side chains similar to that attacked; but these 
side chains are manufactured in greater quantity than is required to neutralise 
the toxin, and those in excess are cast off and appear in the blood as antitoxin. 
This theory demands— 
(a2) That the tissues which are concerned in the production of antitoxin 
are those tissues which the toxin attacks. 
(>) That antitoxin is produced in tissues remote from the seat of 
inoculation. 
