208 TRANSACTIONS OF THE [mAUCH 29, 



sitating hypothetical substances, while, on the other hand, we 

 have to admit that chemistry has not as yet suflBcie:itly inves- 

 tigated the subject to decisively negative their existence. 



There can be no doubt that the cause of this immunity after 

 inoculation, or after one attack of a disease, is in some measure 

 connected with the fact of the immunity of certain animals from 

 particular diseases. Thus the hog or carnivorous animals are 

 not affected by the bacillus of anthrax, so deadly to the hcrbi- 

 vora. Klein is very much justified in believing that this is 

 largely due to difference in the chemical constitution of the 

 blood, but does not, I think, dwell sufficiently on other condi- 

 tions, like temperature, degree of oxygenation, etc., which, apart 

 from difference in chemical constitution, make the blood and 

 tissues of certain animals (juite different culture media. 



It will be remembered that, in the extract quoted from Klein, 

 this particular case of the unsusceptibility of the pig is taken as 

 an analogue of the state of a sheep or ox after once having an 

 attack of anthrax. I would call the attention of Dr. Klein to 

 what may be an unconscious, but what is most certainly a radi- 

 cal shifting of his ground, under tlie necessities forced on him 

 by the adoption of this tiieory, if he really intends that these 

 two cases sliould be considered similar, and that his expression 

 C just as in the case of an animal, say a pig, ... so also in the 

 case of a sheej) or ox" ) should be taken literally. 



That they are not similar, upon his theory of protection, ap- 

 pears from an anah'sis of his remarks on pages 178, 179, and 18G 

 of his book. 



There he says : " The tissues and juices of a pig, Avhen obtained 

 as infusion or otherwise, are just as good a nourishing nuiterial 

 for the bacillus anthracis as the tissues and juices obtained from 

 an herbivorous animal," and ''there remains, therefore, only 

 one thing; that is, there is something or other present in a par- 

 ticular tissue, to which this latter owes its immunity, and this 

 something must, of necessity, be connected with the tissue while 

 alive ; " and lastly, " this inhibitory power is due to the presence 

 of a chemical substance produced by the living tissue." Gi-ant- 

 ing for the argument (though we do not in reality) the truth of 

 this explanation, is it similar to protection after vaccination, on 

 the hypothesis favored by Klein ? Clearly not. AVhat must be 

 the nature of the substance inliibiting anthrax in pigs to satisfy 

 these last quotations ? 



It must be produced by the living tissue in such small amounts 

 at a time that blood introduced into a culture flask direct from 

 the veins does not contain enough to inhibit tlie growth of the 

 bacillus; it must, therefore, to be effectual for this purpose, be 

 constantly elaborated and constantly destroyed, and [in its elabo- 



