1903.] On the Nucleic Acid of the Tliymm Gland. 103 



11. The solution used in experiment 10 was further diluted with an 

 equal volume of 10 per cent, ammonia, when the solution was found 

 to be optically inactive. 



Our observations have shown us, as has been mentioned at an earlier 

 part of this paper, that the diminution or abolition of optical activity 

 which is induced by alkalies in solutions of thy mo-nucleic acid are 

 not permanent, the addition of acid restoring the primitive optical 

 condition. 



Billow has shown* that the optical rotation of proteids varies with 

 changes in the reaction of their solutions, and Frammf studied espe- 

 cially the alteration brought about in the specific rotation of gelatine 

 by the addition of acids or alkalies. The alterations observed by 

 Framni, however, were probably due to fundamental chemical changes 

 brought about by the acid or alkali on the proteid. This reasoning 

 cannot, however, be applied to the case of the nucleic acid of the 

 thymus gland, seeing that the addition of acid to an alkaline solution 

 restores the optical activity. 



At the suggestion of one of us (A. G.), Dr. Thomas B. Osborne { has 

 determined the optical activity of the nucleic acid which he separated 

 from the wheat embryo, and to which he applied the name of tritico- 

 nucleic acid. Dr. Osborne has found that this nucleic acid is 

 dextrorotatory, though the degree of rotation is considerably 

 influenced by the concentration of the solution. A solution containing 

 4 per cent, of tritico-nucleic acid possessed a specific rotation 

 fa] D =4-73. 



* Biilow, " Ueber aschefreies Eiweiss," ' Pfliiger's Archir,' vol. 58 (1894), p. 207. 



t Framm, "Untersuchungen iiber die specifische Drehung des 0-G-lutin," ibid., 

 vol. 68 (1897), p. 144. 



J T. B. Osborne and I. F. Harris, "Die Nucleinsaure des Weizenembryos," 

 ' Zeitschr. f. Physiol. Chemie,' vol. 36, heft 2 (September, 1902), p. 85. 



T. B. Osborne, " The Specific Rotation of the Nucleic Acid of the Wheat 

 Embryo," ' Arner. Journ. of Physiol.,' vol. 9, No. 2 (issued April 1, 1903), p. 69. 



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