Apeil 3, 1903.] 



SCIENCE. 



539 



grouij is a side chain associated with it. 

 Purther, he supposes that the central group 

 has attached to it another side chain which 

 acts as the receiver and transmitter of tha 

 oxygen, and consists of a nitrogenous or iron 

 compound, since certain compounds of either 

 of these elements readily combine with oxygen 

 and yield it up again. A biogen molecule 

 may, then, be pictured as composed of an 

 oxygen receptor and translator, consisting of 

 a nitrogen or iron group, and oxidation ma- 

 terial represented by a carbohydrate group 

 with certain aldehyde-like peculiarities, both 

 these groups being united as side chains 'to a 

 benzol nucleus. 



In such a molecule two varieties of de- 

 structive change may occur: what may be 

 termed functional dissociation, affecting only 

 the carbohydrate side chain, and destructive 

 decomposition, which affects the entire mol- 

 ecule. The latter process necessarily impairs 

 or destroys the activity of the molecule, and 

 is compensated for by the synthetizing powers 

 of the unaltered biogens which, acting on the 

 products of digestion, build up additional 

 molecules by a process of polymerization. 



It is believed that there is no evidence of 

 the existence of biogens in the cell nucleus, 

 although this structure, directly or indirectly, 

 contributes to the maintenance of the metab- 

 olism of the cytoplasm. The active molecules 

 are located exclusively in the cytoplasm, which 

 also contains reserve supplies of nutrition and 

 of oxygen, the latter being in composition, 

 and' it is also supposed that there is present 

 normally a greater or less amount of ma- 

 terial, produced by the action of the cell 

 enzymes, and of such a nature that it can at 

 once be employed in the restitution of the 

 biogen molecules. 



Such is, in outline, the biogen theory, and 

 having expounded it, Professor Verworn pro- 

 ceeds to apply it to the explanation of certain 

 physiological phenomena. He points out that 

 two changes may be recognized as causes in 

 the diminishment of a response to stimuli: 

 (1) A diminution or suppression of the la- 

 bility of the molecules and (2) a diminution 

 or suppression of the supply of restitution 

 material. The characteristic symptom of the 



first of these causes is a gradual rise in 

 strength of the minimal stimulus during the 

 development of the phenomenon, while that 

 of the second is the occurrence during its 

 development of constantly increasing intervals 

 during which the tissue fails to respond to the 

 stimulus. On this basis a distinction, already 

 drawn on somewhat similar lines by an Amer- 

 ican physiologist, is made between fatigue and 

 exhaustion, the latter being regarded as due 

 to the imperfect restitution of the molecules, 

 while the former is the result of an impair- 

 ment of their lability, owing to an accumula- 

 tion in the tissues of catabolic substances 

 which act as narcotics. For it is claimed that 

 the effect of narcotics in general is an inhibi- 

 tion of the lability of the biogens. 



It would carry us too far to follow the 

 author into his application of the theory to 

 the explanation of the phenomena of the self- 

 regulation of metabolism, of rhythm and of 

 the source of muscular energy. Suffice it to 

 say that these subjects are treated with the 

 same clearness and suggestiveness as distin- 

 guish the remainder of the paper. Professor 

 "Verworn is careful to insist that his theory 

 claims merely the rank of a working hypoth- 

 esis, and, viewed in this light, it should serve 

 a purpose in stimulating further investiga- 

 tion. Its similarity to Pfliiger's hypothesis 

 has been already noted; indeed, it might be 

 characterized as Pfliiger's theory expressed 

 with greater precision and combined with an 

 idea borrowed from Ehrlich's well-knovsm 

 theory of immunity. One may question the 

 advisability of substituting the single chem- 

 ical compound biogen for the more complex 

 protoplasm as the material basis of vital en- 

 ergy, and it may be claimed that the assumed 

 structure of the biogen molecule is altogether 

 too schematic; but, nevertheless, it will be 

 admitted that the paper is full of interest and 

 suggestion, and even though the future may 

 show the theory to be futile, it must be re- 

 membered, as the author points out, that ' for 

 the development of human intellectual life 

 a fertile error has infinitely greater value 

 than an unfertile fact.' 



J. P. Mcll. 



