656 THE INTERNAL SECRETIONS AND IMMUNITY. 



"Third class: Leucomaines of animal bases. 



(a) Neurin leucomaines. 



(b) Creatin leucomaines. 



(c) Xanthic leucomaines. 



(d) Unclassified leucomaines. 

 Appendix: Ptomaines. 



"Fourth class: Ureides. 

 Mono-ureides. 

 Di-ureides, etc. 



"We do not intend to describe these substances, but sim- 

 ply indicate the origin of each, the principal ways in which they 

 are split, and their role in the economy. 



"First Class: Albuminoid Derivatives. (a) Peptones. 

 We have seen that proteid substances when split by hydration, 

 are converted into peptones in the intestine, and that, though 

 much lower in molecular weight than their antecedent albu- 

 minoids, these peptones nevertheless preserve the general char- 

 acters of the latter. They represent their immediate deriva- 

 tives. 



"As is the case with proteid substances, peptones contain 

 five elements: carbon, hydrogen, oxygen, nitrogen, and sulphur 

 in analogous proportions; they also tend, as do the former, to 

 become transformed into complex amids that accompany urea 

 and oxamids, which can undergo autoconversion, if hydration 

 continues, into carbonate and oxalate of ammonia. By means 

 of further hydration peptones may be split up into acid amids 

 leucin, glycocoll, tyrosin, etc. and ammoniacal salts. They 

 give the Millon and biuret reactions. They are, therefore, 

 essentially albuminoid. 



"These very distinct basic properties of peptones, that are 

 hardly perceptible in the albuminoids from which they are 

 derived, make them the first term of the series of animal bases 

 or leucomaines. Before I had discovered the latter substances, 

 the basic properties of peptones were practically unperceived, 

 or, at least, they failed to attract interest; but to-day we are 

 aware that, besides these alkaloidal characteristics, peptones 

 are likewise toxic in rather large doses. Toxins, venoms, dias- 

 tases, secreted by microbes, white corpuscles, and certain glands, 



