4 THE SIMPLER NATURAL BASES 



are devoted entirely to animal bases, Chapter V dealing with creatine, 

 creatinine, and other guanidine derivatives, and Chapter VI with 

 adrenaline, one of the most interesting of simple bases. 



Twenty years ago it could hardly have been imagined that the 

 suprarenal gland constantly secretes into the blood minute quantities 

 of a base having an intense physiological action, and that this base 

 has a simple chemical constitution and can be synthesised. At first 

 adrenaline stood entirely by itself; later some of the putrefactive 

 amines of Chapter I were found to have considerable physiological 

 activity, and one of them, p-hydroxy-phenyl-ethylamine, which 

 resembles adrenaline chemically, was found to have an essentially 

 similar, although weaker, action on the animal organism. There are 

 moreover indications that other internal secretions owe their activity to 

 bases of comparatively small molecular weight. This appears to be 

 the case with the highly active principle of the pituitary body which 

 is possibly a histidine derivative, and shows some analogies to fi- 

 iminazolyl-ethylamine described in Chapter I. Unfortunately hardly 

 anything is known with regard to the chemistry of the pituitary active 

 principle, so that it is only included in Chapter VII (bases of unknown 

 constitution) on account of its physiological importance. Secretine, 

 the substance which when introduced into the blood stream, causes 

 secretion of pancreatic juice, is probably also a base and like the active 

 principles of the adrenal gland and of the pituitary body, it is moder- 

 ately stable in boiling aqueous solution. 



The case of the bacterial toxins and antitoxins, which are rapidly 

 destroyed below the temperature of boiling water, is very different. 

 After working on the products of putrefactive bacteria, Brieger in- 

 vestigated the bases produced in cultures of pathogenic organisms, 

 such as the typhoid and the tetanus bacillus, but the simple bases 

 which he obtained could not be regarded as the principal cause of 

 disease, and his further work on tetanus toxin showed this substance 

 to be extremely active and apparently also extremely complex. We 

 may say " apparently " for the following reason. When a minute 

 quantity of an active principle accompanies large quantities of proteins 

 and other colloids it may remain adsorbed on these in such a way as 

 to make a separation impossible, even when the active principle has a 

 comparatively small molecular weight. The difficulties are particularly 

 great when the active principle is very soluble in water but hardly at 

 all in alcohol, as is often the case with bases of the animal body. A 

 good deal of optimism is required for the belief that our present 

 methods will ever suffice for the isolation of bacterial toxins in a state 



