STUDY OF RESPIRATION BY INHIBITORS 383 



tion of bacteria which contain cytochromes is inhibited by cyanide 

 though Httle in the case of Vorynebacterium diphtheriae and (\ pseudo- 

 diphthericum (962). 



The degree of cyanide inhibition of the respiration of retina has been 

 claimed to depend markedly on the medium (phosphate or bicarbonate) 

 (.1652). Similar observations have been made with other mammalian tissues 

 (39,596), but presence or absence of substrate (glucose) was probably the 

 decisive factor (c/. ^69,1479,1541). 



5.5. Importance of the Cytochrome System for Supply 

 of Energy and Cell Function 



Whether the respiration of the resting cell is always catalyzed by 

 the cytochrome system or not, it has become increasingly clear that 

 the functional activity of the cells depends on this system. 



The respiration of fertilized Arbacia eggs, abolished by cyanide, 

 can be restored by methylene blue or pyocyanine, but the ability of 

 the cell to develop and to divdde is not restored (1572). x\nother 

 instructive example is the development of grasshopper eggs, in which 

 a cyanide and CO-sensitive cytochrome respiration is correlated 

 with the prediapausal and postdiapausal development, while during 

 the diapause the lower residual respiration is cyanide and CO-in- 

 sensitive (304-306; cf. also 3017, p. 578 ff.). Needham (3017) con- 

 cludes: "It almost looks as if nonferrous respiration cannot be geared 

 to morphogenesis." 



Similar results were obtained with regard to the respiration of the 

 frog nerve by Schmitt (2447,2450). The cyanide-suppressed respira- 

 tion of frog nerve is restored by methylene blue, but not its action 

 potential. Cyanide and carbon monoxide inhibition abolish the 

 potential together with the respiration, while illumination of carbon 

 monoxide inhibited nerve restores both. "Spike" and "after poten- 

 tial" are maintained by the same respirsttory catalyst (2448). Sus- 

 tained tonic contraction of smooth muscles also requires the active 

 cytochrome system (244-9). 



The embryologic studies of P'lexner and Stiehler (906-908,2431, 

 2664) are of particular interest in this connection. In the chorioid 

 plexus of the fetal pig, in the presecretory phase when the spinal fluid 

 is still an ultrafiltrate, not a secretion, there is no diflFerentiation in the 

 distribution of the cytochrome oxidase system between epithelium 

 and stroma and no potential difference. Later in the secretory phase, 

 the oxidase .system is concentrated in the epithelium and a positive 



