148 SCIENCE PROGRESS. 



not yet been determined. Carnic acid x is of some consider- 

 able interest. It is free from sulphur having a formula 

 C IO H I5 N 3 5 ; it gives the biuret but not Millon's reaction. 

 It forms an addition compound with one molecule of hydro- 

 chloric acid in which the chlorine is not precipitated by silver 

 nitrate until it is boiled with nitric acid. It thus gives all 

 the reactions of antipeptone with which Siegfried considers 

 it identical, a view which is confirmed by Frankel % who 

 finds that antipeptone when prepared pure by the artificial 

 digestion of proteids is sulphur free. Siegfried compares 

 phosphocarnic acid to the nucleins, pointing out that where 

 the nucleins yield proteid phosphocarnic acid yields antipep- 

 tone and he therefore suggests for it the name nucleon. 

 Siegfried considers that the muscle-nucleon or some com- 

 pound of it plays an important part in the metabolism of 

 muscle during its activity, for he finds that its amount is 

 much less in fatigued than in resting muscle and points out 

 that the formation of carbonic acid, phosphoric acid, and 

 lactic acid during a muscle's activity can be at once explained 

 as the result of the decomposition of phosphocarnic acid. 

 This view is further strengthened by the experiments of 

 Kruger 3 who shows that muscle-nucleon on hydrolysis gives 

 off considerable quantities of carbonic acid and that no other 

 extract from muscle does this. For this production of car- 

 bonic acid no oxygen is required. 



Phosphocarnic acid has also been prepared from the 

 urine 4 where it is present in very small quantities and also 

 in milk. 5 The nucleon obtained from the latter source is 

 however a slightly different structure, for it yields on decom- 

 position fermentation lactic acid in the place of paralactic. 

 From the fact that it yields antipeptone on decomposition 



1 Siegfried : Ber. d. k. Sachs. Ges. d. JViss. zu. Leipzig. Math.-Phys. 

 Classe., 1893, S. 485 ; Arch. f. {Anat. u.) Physio/., 1894, S. 401, and Ber. 

 d. d. chem. Ges., Bd. 27, S. 2762, 1895. 



2 Frankel: Wiener. Med. Bl'dtt., 1896, S. 703. 



3 Kruger : Ztschr. f. physiol. Chem., Bd. 22, S. 95, 1896. 



4 Rockwood : Arch. f. (Anat. u.) Physiol., 1895, S. 1. 



5 Siegfried: Loc. cit. and Ztschr. f. physiol. chem., Bd. 22, S. 575, 

 1896. Wittmaack, ibid., Bd- 22, S. 567. 



