188G.J NEAV YORK ACADEJIY OF SCIEKCES. ^211 



in returning a " tu quoque '' and asking liow mucli investi- 

 gation of tlie functions and potencies of tlie various classes of 

 cells under the above variations have been made b^^ physiologists. 

 All that either of us know absolutely in connection with the 

 subject is that an effect has changed, and there must therefore 

 be a variation in the cause. And so I will make bold, in sjjite 

 of impossibilities of conception, to state the third theory, 

 brought into jirominence in America by the writings of Stern- 

 berg, and simply say that while this, in common with all, has to 

 sup})ose some things yet unproved, this, alone of all, is not con- 

 tradicted by the facts of our present knowledge. It is called by 

 Sternberg a "vital resistance theory,'' but since vital resistance 

 is recognized even by the advocates of the other theories, and, 

 as considered now, acquired tolerance is the characteristic 

 feature, we will, for our purposes, call it the "tolerance" 

 theory. The theory is simply this: Non-pathogenic organisms 

 differ from pathogenic in that the former are not able to with- 

 stand the influence of the healthy tissues of an animal. To 

 what is this difference, admitted by all, due ? Probably to the 

 production by the pathogenic organism of some chemical sub- 

 stance not elaborated by non-pathogenic or septic organisms. 

 Here we are not at variance with the majority of observers^ 

 What, then, is more natural than that the immunity after a first 

 attack or after inoculation Avitli mitigated virus proceeds from 

 an acquired tolerance to this particular chemical substance. Let 

 it be clearly understood that these disease germs are cells, that 

 they meet in the tissues other cells, that the blood is simply 

 blood-discs, peculiar cells, floating in the serum, and that in 

 disease there is a contest between these different cells. Suppose, 

 now, the disease cells elaborate, as they probably do, certain 

 organic substances deleterious to the cellular constituents of the 

 tissues and blood, is it not very possible, is it not certain, in fact, 

 to a limited extent, that where, in any such combat, the animal 

 cells were victors over the disease germs, the cells would acquire 

 some tolerance to the deleterious substance ? Look at the quick 

 tolerance of the cells to organic poisons! 



The opium habit can be very quickly acquired, I understand, 

 so that doses fatal to the normal man are almost harmless. Again 

 I understand from smokers that the tobacco sickness experi- 

 enced with the first cigar protects in some singular manner from 

 subsequent attacks, and these illustrations are exactly to the 

 point, since we are dealing Avith the acquired tolerance of the 

 system (which is simply an infinitude of cells), or of the cells 

 themselves to organic poisons, and I wish to show that in some 

 cases this tolerance is quickly established. Place now beside 

 this Dr. Klein's, "it is impossible to imagine that the cells of 



