384 CHEMISTRY OF THE PROTEIDS CHAP. 



it behaves as does any other coagulated albumin. As long as it is not 

 coagulated, it is to a certain extent soluble in acids l and alkalies, 

 according to Limbourg, 2 and also in urea, according to Spiro. 3 This 

 passing into solution depends, however, probably on the formation of 

 acid-albumins and of alkali -albumiriates, while its solution in very 

 dilute acids and alkalies, as well as in salts (Fermi, Limbourg), must 

 be explained as due to the presence of>proteolytic ferments or their 

 zymogens, which are absorbed into the blood, and which are preci- 

 pitated on the fibrin whenever the latter is formed. Fibrin also 

 frequently encloses considerable amounts of serum-globulin, which is 

 liberated when fibrin is digested, and this liberated globulin led the 

 older investigators to state that globulin was the first product of fibrin- 

 digestion. Pepsin and trypsin attack fibrin with great readiness, and 

 attention has already been drawn to the fact that fibrin has been 

 used for many experiments on digestion. Witte-peptone is said to be 

 digested fibrin. 



Halliburton 4 prepared from the blood of crayfish a fibrinogen, 

 which, apart from having a coagulation - temperature of 65, behaves 

 in every other respect as does that of vertebrates. Loeb 5 has 

 studied the resemblances and the differences in the coagulation of 

 the blood of vertebrates (guinea - pig, birds) and invertebrates 

 (arthropods). 



V. THE MUSCLE-ALBUMINS 



The fluid contents of the sarcolemma-sheaths of striped muscle, 

 or the sarcoplasma, contains peculiar albumins in solution, which were 

 first investigated by Kiihne, 6 and then by Halliburton 7 and v. Fiirth. 8 

 Kiihne prepared a muscle-plasma by freezing frog-muscles, and then 

 pounding them to break up the sarcolemma - sheaths. From the 

 plasma so obtained he isolated myosin, which, by coagulating 

 spontaneously, passes over into a fibrin-like modification. Eigor 

 mortis depends on the coagulation of this myosin. The coagulated 



1 C. Fermi, Zeitschr. f. Biol. 28. 229 (1891) ; G. Wolffhiigel, Pfliiger's Arch. 7. 188 

 (1873). 



' 2 P. Limbourg, Zeitschr. f. physiol. Chem. 13. 450 (1889). 



3 K. Spiro, ibid. 30. 182 (1900). 



4 W. D. Halliburton, Journ. of Physiol. 6. 300 (1885). 



5 Leo Loeb, Hofmeister's Beitrage, 5. 191 and 534 (1904). 



6 W. Kiihne, Arch. f. (Anat. .) Physiol. 1859, p. 748 ; Text-book of Physiological 

 Chemistry, p. 272 (1868). 



7 W. D. Halliburton, Journ. of Physiol. 8. 133 (1887) ; German translation of text- 

 book of physiology by K. Kaiser, 1892, p. 425. 



8 0. v. Ftirth, Arch. f. experim. Pat/wl. u. Pharm. 36. 231 (1895) ; Zeitschr. f. 

 physiol. Chem. 31, 338 (1900) ; Ergebnisse der Physiologic, I. 1. 110 (1902) ; Hof- 

 meister's Beitrage, 3. 543 (1903). 



