THE MUSCLE- ALBUMINS. 351 



has not been ascertained, but is very probable. Some writers indeed 

 regard the coagulation of muscle-plasma which occurs on standing as 

 being referable to the presence of such an enzyme. 



Other Albumins. Besides myosin and myogen, which latter was 

 formerly termed myosinogen, muscle-plasma was also supposed to 

 contain traces of serum-albumin, myoglobulin, and myo-albumose. 

 v. Fiirth, however, has shown that any trace of serum-albumin that 

 may be found is referable to the presence of small amounts of lymph 

 or blood that have not been removed by washing, and that if this is 

 done with special care no serum-albumin can be demonstrated. 

 Halliburton's myoglobulin, moreover, he regards as identical with 

 myogen, while the existence of a myo-albumose in muscle-plasma 

 has been disproved by more recent investigations. That substances 

 belonging to the albumoses'may be found in muscle-tissue after death, 

 when syntonin also is found, is, of course, likely, but in the living 

 tissue their presence can hardly be expected under normal conditions. 



Myoproteid is a substance which v. Fiirth obtained from the 

 muscle-plasma of fish. Of its chemical nature, however, nothing 

 further is known than the fact that it apparently does not belong to 

 the commonly recognized classes of albumins. It is neither a 

 nucleo-albumin nor a glucoproteid. 



Nucleins are not found in the muscle-plasma, but can be isolated 

 from the muscle-tissue as a whole or from the insoluble material 

 which remains in the filter-press after separation from the plasma. 

 Their amount is small, and in accordance with the slight degree to 

 which the nuclei enter into the structural composition of the muscle- 

 cell. Larger amounts are obtained from embryonic muscle, where 

 cellular reproduction is, of course, more active. From the tissue of 

 an adult dog Pekelharing obtained about 0.37 per cent. These 

 nucleins must be regarded as the material from which the xanthin- 

 bases that can always be demonstrated in muscle-tissue are derived. 

 These will be considered in detail later. 



Phosphor-carnic Acid. A few years ago Siegfried announced 

 that after removing the phosphates from extracts of muscle-tissue, 

 and treating with ferric chloride, under the application of heat, a 

 phosphorus-containing iron compound is obtained, which is insolu- 

 ble in water, but easily soluble in solutions of the alkalies. This 

 substance he regards as the iron salt of an organic acid, which he 

 terms phosphor-carnic acid ; the salt he speaks of as carniferrin. 

 On decomposition with barium hydrate he then obtained the barium 

 salt of a crystallizable acid, carnic acid, to which he gives the 

 formula C 10 H lr) N.,O. v In addition, phosphoric acid, carbonic acid, 

 paralactic acid, succinic acid, and a substance which apparently 

 belongs to the carbohydrate group, are found. In his more recent 

 communications Siegfried expresses the opinion that his carnic acid 

 is in reality pure antipeptone. This question is still under debate, 

 and is strongly combated by Kutscher and others. Kutscher, 

 indeed, has shown that Kiihne's antipeptone is in reality a mixture 



