646 THE INTERNAL SECRETIONS AND IMMUNITY. 



After reviewing the various hypotheses that have been 

 proposed that the antitoxin is the toxin itself, but in a modi- 

 fied form; that it is an enzyme produced in the culture; that 

 it is a product of cellular activity McFarland concludes, in 

 accord with the prevailing opinion, that "probably the best 

 explanation of the histogenesis of the antitoxin" is Ehrlich's 

 lateral-chain theory. Indeed, some of the points made may 

 be adduced as evidence in favor of the latter. The phenomena 

 observed in the horse that furnished serum containing 1400 

 units, then 100 units, may be explained, for instance, by the 

 exhaustion of cataphoric atoms: a feature of the process which 

 simultaneously suggests its dependence upon the body-cells for 

 the formation of the antitoxin. Yet, while the same reasons 

 are applicable when the adrenal system is brought into the 

 process, suggesting at the same time that normal adrenals 

 can produce a large amount of secretion, then become weakened 

 without lapsing into sudden insufficiency, it is difficult, with 

 Ehrlich's theory, to account for the sudden sensitiveness ob- 

 served, without indulging in pure conjectures based upon hypo- 

 thetical deductions. The overwhelming evidence adduced as 

 to the tendency of the adrenals to suddenly cease their func- 

 tions and give rise to symptoms similar to those observed in 

 the injected animals, on the other hand, the sudden deaths in 

 Addison's disease, those that occur as the result of haemor- 

 rhage into the adrenals, etc., emphatically point to adrenal 

 insufficiency as its source. Adrenal insufficiency here obviously 

 means that the oxidizing substance is a main factor of the 

 entire process. 



Indeed, that the presence of the oxidizing substance in 

 the blood-serum accounts for a large number of reactions the 

 nature of which has not, so far, been satisfactorily explained, 

 seems undeniable. The long list of chemical agents which 

 have been shown by Schmiedeberg, Salkowski, Jaquet, Lan- 

 glois and Biarnes, among others, to be oxidizable through 

 contact with various tissues and blood-serum represents but a 

 diminutive proportion of the bodies that can be converted 

 through a similar process into dissimilar compounds. Uric 

 acid, we have seen, is the end-product of a series of reactions 

 of this kind: a benign agent developed by oxidation from toxic 



