444 CHEMISTRY OF THE PROTEIDS CHAP. 



a rule, the barium salt. Bang has investigated the silver salt of guanylic 

 acid. The equivalent weight of the nucleic acids is between 300 and 

 600, while the molecular weight must be much higher. 



Kossel 1 has pointed out that the salts of the nucleic acids, 

 especially that prepared from the leucocytes of the thymus, possess 

 the remarkable physical property of forming jellies or mucilaginous 

 solutions. According to Plenge, 2 a 5 per cent solution of sodium 

 nucleate on being cooled to 42 solidifies into a glassy, perfectly 

 clear, firm, gelatinous jelly, and 2*5 per cent solutions solidify also if 

 they contain sodium chloride or bouillon made by extracting meat with 

 water and then adding peptone. Plenge has made use of this sodium 

 nucleate for preparing culture media which remain solid at 37. 



If the solution contains still less nucleic acid it does not set into 

 a firm jelly; but, especially in the presence of albumin, it possesses a 

 marked viscous consistency reminding one of mucin-solutions. The 

 blood of birds solidifies on the addition of caustic-soda solution into a 

 jelly, owing to the nucleic acid contained in the nuclei of the red^ 

 corpuscles; and even human blood^ has a tendency towards jelly 

 formation, especially if the number of leucocytes be excessive. The 

 same holds good for urine 4 rich in leucocytes. 



The nucleic acids and their derivatives, the nucleins and nucleo- 

 proteids, are dextro-rotatory, as Gamgee and Jones 5 have found. The 

 albumin-moiety is laBvo-rotatory, but the dextro-rotatory power of the 

 nucleic acid is greater. The salts of nucleic acids with albumin 

 are the most important, for they occur normally in the heads of 

 the spermatozoa of fish, and perhaps also in other situations. The 

 albumin salts are insoluble ; but they behave analogously to the salts 

 which albumins form with the alcoloidal reagents, i.e. they dissociate 

 hydrolytically if an excess of acid be not present. Nucleic acid, 

 therefore, precipitates albumin only if the reaction be acid, and not 

 if the reaction be either alkaline or neutral. 



From the experimental- his tological point of view, protamins, 

 nucleins, and nucleic acids have been very thoroughly investigated 

 by Berg. See also Wetzel. 7 



1 A. Kossel, Arch.f. (Anat. u.) Physiol. 1891, p. 181 ; A. Neumann, ibid. 1899, 

 Suppl. p. 552. 2 H. Plenge, Zeitschr.f. physiol. Chem. 39. 190 (1903). 



3 C. Hirsch and E. Stadler, Zeitschr. f. physiol. Chem. 41. 125 (1904). 



4 Job. M tiller, Munchener medizin. Wochenschr. 1903, p. 1360. 



5 Arthur Gamgee and Croft Hill, Ber. d. deutsch. chem. Ges. 36. 913 and 914 

 (1903) ; A. Gamgee and W. Jones, Hofmeister's Beitrage, 4. 10 (1903) ; see also T. B. 

 Osborne, Amer. Journ. of Physiol. 9. 69 (1903). 



6 Walter Berg, Arch.f. unk. Anat. 62. 367 (1903), and 65. 298 (1904). 



7 J. Wetzel, Arch. f. (Anat. u.} Physiol. 1904, p. 544 ; and in Verh. d. physiol. Ges. 

 zu Berlin, 10. p. 71. 



