258 



ferment, the other that of an enzyme-substrate to be decomposed by that ferment. The 

 ferment-like substances are called anti-bodies, the various substrates they act upon, 

 antigens. 



In my opinion there is however no sufficient ground also to call the antigens and 

 the complement enzymes, as is done by several investigators. 



If these substances are considered as enzymes only because of their action after 

 injection into the blood of higher animals, it will be necessary, in order to be consi- 

 stent, likewise to bring to the enzymes toxins and even some common coagulable 

 proteids, which would make this word lose its real significance. Whereas in the 

 descriptive sciences the necessity is felt to designate by special names even but slightly 

 differing objects, it would be an error to attribute to the words enzyme and ferment 

 a continually varying and wider meaning no more in accordance with the original con- 

 ception. On the other hand it is clear that further knowledge about the enzymes or 

 factors may necessitate the creation of new names to mark the vast differences between 

 them, as now we are already compelled to use the words exo- and endoenzymes. 



There is still another group of bodies worth being considered from the new point 

 of view, namely the viri in general and in particular those of plant diseases, such as 

 the mosaic disease of the tobacco. They clearly belong to the enzymes or factors, 

 although commonly not hereditarily transported. But the further discussion of this 

 point must be deferred to later. 



The only place in literature, hitherto come to my knowledge, where an hypothesis 

 is indicated somewhat corresponding to my view, is to be found in B a t e s o n. He 

 says 1 ): Uber die physikalische Natur der Erbeinheiten konnen wir noch nichts aus- 

 sagen; die Folgeerscheinungen ihrer Gegenwart sind aber in so vielen Fallen mit den 

 durch Fermente hervorgerufenen Wirkungen vergleichbar, dass wir mit einiger Be- 

 stimmtheit annehmen, dass die Fahigkeiten einiger Erbeinheiten im wesentlichen in der 

 Bildung bestimmter Substanzen bestehen, welche in der Art von Fermenten wirken. 



Although the observations on which this statement is based are in accordance 

 with the enzyme theory, it is clear that B a t e s o n's view is quite different from mine. 



') W. Bateson, Mendel's Vererbungstheorien, pag. 269, 1914 (Translation of the 

 English edition of 1909). 



