A THEORY OF THE NATURE OF PROTOPLASMIC 

 RESPIRATION AND GROWTH. 



A. P. MATHEWS. 



Respiration is probably the most fundamental of living pro- 

 cesses. It is common to all forms of protoplasm ; as long as it 

 persists, protoplasm is said to live ; when it ceases protoplasm 

 dies ; and it is the point of attack of the most powerful poisons 

 such as the isocyanides. Most of the other protoplasmic func- 

 tions depend directly or indirectly on respiration as, for example, 

 the discharge of impulses from the nerve cells, the beating of the 

 heart and so on. The protoplasmic syntheses and many of the 

 decompositions have been ascribed since Drechsel's work and 

 that of Hoppe-Seyler to this fundamental process. 



In any general theory of respiration the following facts have 

 to be explained : 



1. Even though surrounded by oxygen all protoplasm main- 

 tains itself while alive in a reduced state and acts as an intense 

 reducing agent. Its reducing powers are comparable to those 

 of nascent hydrogen. 



2. For all forms of protoplasm free oxygen above a certain 

 tension is an intense poison. For some forms this tension may 

 be no more than a very small fraction of an atmosphere ; for 

 others it is from three to four atmospheres. 



3. Atmospheric oxygen has little oxidizing power; whereas 

 protoplasm brings about oxidation of the most radical nature 

 and is comparable in its oxidizing powers to the most intense 

 chemical oxidizing agents. 



4. Hydrogen is evolved as a gas by a great variety of bacteria 

 and moulds. 



5. The production of carbon dioxide by protoplasm stands in 

 no direct or immediate relation to the consumption of free 

 oxygen. 



6. Many forms of protoplasm such as the anaerobic bacteria 

 are able to bring about intense oxidations in the absence of 

 atmospheric oxygen. 



