284 SHIRO TASHIRO. 



with chemical phenomena has been set forth long ago. Pro- 

 fessor Mathews, in his paper on "Animal Oxidation," expressed 

 the idea that cellular respiration must be the fundamental process 

 of all organic activity around which all functional phenomena are 

 intimately connected. Later in his study on the action of ether 

 and other anaesthesias on an anaerobic tissue he confirmed his 

 idea that all the substances that affect irritability must neces- 

 sarily attack the tissue respiration first. With the aid of the 

 new apparatus, the direct evidence for his hypothesis has been 

 brought forth in connection with the study of metabolism of the 

 nerve fiber, in which three fundamentally interesting facts have 

 been established. In the first place, the most excitable tissue 

 of all the protoplasm, the nerve fiber, is constantly undergoing 

 chemical changes, giving off CCV In the second place, when 

 this tissue is stimulated COa production is greatly accelerated, 

 giving more than double the amount. Finally, the rate of COa 

 is greatly influenced by conditions such as anaesthesia, which 

 are known to affect tissue irritability, showing a direct relation 

 between respiration and excitability. 1 



Before I had concluded, from these facts, that all the irritable 

 tissues must respire and should give off more COo when stimu- 

 lated, a crucial experiment was done on a dry seed. Waller's 

 conclusion has been fully realized. A living dry seed not only 

 gives off COo quantitatively proportional to its weight, but also 

 gives off more COo when stimulated, a phenomenon true to living 

 seeds only. These facts enable me to propose a new sign of life, 

 namely, a chemical sign. The criterion is simple. If we are 

 given a tissue which gives more COz when stimulated, the tissue 

 must be alive; it is excitable. A discovery of a remarkably 

 simple method of stimulation made this chemical sign of life 

 much more easily practicable to all living tissues. Simple 

 mechanical crushing of the living tissue is the new method. I 

 have already argued elsewhere 2 that the phenomenon that the 

 nerve gives off more COz when crushed, is due mainly to an 

 extreme stimulation and that it is characteristic of living, 

 excitable tissues only. Therefore without any attempt to settle 

 the question as to how CO 2 production is increased, we can use 



1 Am. J. of Physiol., XXXII., pp. 107-136, 1913. 



2 Am. J. of Physiol., XXXII., p. 121, 1913. 



