140 SCIENCE PROGRESS. 



boiled with dilute sulphuric acid. It shows a further 

 difference from the nucleic acid from which it is obtained 

 by yielding no carbohydrate molecule. It has not at 

 present been prepared from nucleic acids derived from 

 other sources. Its formula is given as C I5 H 28 N 6 P 6 30 , and 

 thus shows a relatively higher amount of phosphorus com- 

 pared to nitrogen than either nucleic or thyminic acids. 



We see then that nucleic acid is a very complex body 

 which is moreover characterised by the ease with which it 

 can be broken down into simpler and more stable molecules. 

 Hence its preparation for purposes of analysis requires con- 

 siderable care, and the formulae which have been given 

 for it can only at present be regarded as approximate. 

 Miescher's formula for " salmonucleic acid" as recorded by 

 Schmiedeberg 1 is C 40 H 54 N I4 P 4 27 and for a sample of yeast 

 nucleic acid prepared by Altmann, Miescher- obtained the 

 formula C 40 H 54 (OH) 5 N I4 P 4 27 which only differs from that 

 of salmonucleic acid by 5 ( — OH). The formulas given by 

 Kossel are somewhat different. Thus for nucleic acid from 

 yeast he gives a either C 17 H 26 N 6 P 2 I4 or C 25 H 36 N 9 P 3 20 , 

 and for that from the thymus 4 C 30 H 52 N 9 P 3 I7 . Recently 

 Mathews 5 working under Kossel has prepared a nucleic 

 acid from the spermatozoa of an Echinoderm, Arbacia, and 

 finds that the analyses of this agree completely with the 

 later formula given by Miescher for that from salmon 

 spermatozoa. 



THE COMPOUNDS OF NUCLEIC ACID FOUND IN 

 DIFFERENT CELLS. 



Having considered the structure of nucleic acid we may 

 next examine the different combinations in which it is found 

 in different cells. In different positions they are found com- 

 bined with proteids, or with bases belonging to the group 



1 Miescher : Arch.f. exp. Path. u. Pharm., Bd. 37, S. 121, 1896. 



2 Loc. cit., S. 122. 



3 Kossel : Arch.f. (Anat. u.) Physiol., 1891, S. 181. 



4 Kossel : Ibid., 1893, S. 157. 



5 Mathews : Zeitschr.f. chem. Physiol., Bd. 23, S. 399, 1897. 



