570 TISSUE RESPIRATION 



in his living protein combine to form cyanogen radicals, 

 which are entirely absent in the ' ' dead ' ' protein. The prin- 

 cipal argument advanced in support of this view, to the 

 effect that disintegration products of the living protein like 

 urea, creatin and nuclein bases in some instances contain 

 the cyanogen radical, and in some instances can be produced 

 artificially from cyanogen compounds, seems to the author 

 decidedly open to question. Verworn in his biogen theory 

 has formulated views which are somewhat better defined. 

 "By the intramolecular addition of inspired oxygen the 

 biogen molecule finally arrives at the maximum of its readi- 

 ness to undergo decomposition, so that only very slight influ- 

 ences are required to bring about the union of the oxygen 

 atoms with the carbon of the cyanogen. The material of the 

 non-nitrogenous groups of atoms afforded by the explosive 

 decomposition of the biogen molecule can easily be regener- 

 ated by the residue of the biogen molecule from the carbo- 

 hydrates and fats that are present in the living substance. 

 If, finally, the living substance dies, with the absorption of 

 water, the labile cyanogen-like compound of nitrogen passes 

 over again into the more stable condition of the ammonia 

 radical, the nitrogen uniting with the hydrogen of the 

 water. >' 36 



On the other hand for several decades Low has main- 

 tained the hypothesis that the labile character of living 

 protoplasm depends upon a coexistence of aldehyde groups 

 and amino groups. 37 The basis assumed for this hypothesis 

 is somewhat as follows : First, the fact that amino aldehydes, 

 CH 2 .NH 2 



as the compound I , are very labile substances ; again, 



COH 



living, in contrast to dead, protoplasm may be held to show 

 its aldehyde nature in its ability to reduce dilute alkaline 

 silver solutions; and finally those substances which either 



38 M. Verworn, Allgem. Physiol., 2d ed., p. 489, 1897; Lee's Amer. Ed., 

 p. 483, 1899. 



87 O. Low, Die chemische Energie der lebenden Zellen, 2d ed., Stuttgart, 1906. 



