Carbon Dioxide From Nerve Fibres 135 



roundings to form an organic peroxide, and by the help of a peroxidase 

 can transer this to amino acid and carbohydrate molecules bound up 

 in the tissue, just as H 2 O 2 54 can oxidize, with the help of an activator, 

 an acid of formula R. CHNH 2 COOH to C0 2 , NH 3 and an aldehyde 

 RCHO, and then oxidize this aldehyde to RCOOH and ultimately to 

 CO 2 and H 2 O. Poisons such as HNC, NaHS0 3 and NaF, which he 

 found to decrease CO 2 production, temporarily paralyzed respiration, 

 he thought, by uniting with aldehyde groups, while formaldehyde, acid 

 and alkali temporarily paralyze C0 2 forming power of the tissue by 

 destroying the peroxidase. The organic peroxide, though it can still 

 affect some oxidation, cannot of itself carry it to the final C0 2 stage. 

 Recovery of CO 2 forming power is due to the regeneration of the 

 peroxidase. 



Although I doubt that such a process occurs in nervous respiration, 

 the idea of two similar metabolic phenomena involved in the nervous 

 metabolism is very helpful to understand the behavior of the nerve 

 during continued activity. Most recently Tait discovered that a 

 refractory period has two phases, absolute and relative. 55 When 

 he treated the sciatic nerve of a frog with yohimbine, the relative 

 phase is greatly prolonged, while the absolute one is little affected, 

 a result quite different from other common anaesthetics. Waller 56 

 has already observed that protoveratrin slows up the positive 

 variation of the nerve, while the negative variation is little in- 

 fluenced. Waller contends that this drug does not alter cata- 

 bolic change, but retards anabolic activity to a considerable 

 degree. Since pharmocological action on animals of protoveratrin 

 and yohimbine are very similar, Tait concludes that these drugs 

 must attack the nerve in similar manner, and that a refractory period, 

 too, must consist of two phases corresponding to the catabolic and 

 anabolic processes which Waller observed in the case of protovera- 

 trinized nerves. Thus, he considers that his " absolute phase" of 

 the refractory period corresponds to negative variation or catabolic 

 process of the nerve, and the " relative " to the positive return or 

 anabolic. Yohimbine, in other words, retards anabolic processes con- 

 siderably, thus prolonging the refractory period, or increasing nerve 



64 DAKIN: Journal of biological chemistry, 1908, iv, pp. 63, 77, 8 1, 227. 

 55 TAIT: Journal of physiology, 1912, xl, p. xxxviii. 

 66 WALLER: Brain, 1900, xxiii, p. 21. 



