284 LECTURE XIII. 



The proof that such a state of combination exists in the nucleic acid 

 molecule is not satisfactory. Other possibilities exist. Burian has, never- 

 theless, shown that such a linkage is probable. 



In discussing the proteins, we found that a knowledge of the amino 

 acids participating in the constitution of the individual albumins often 

 gave us valuable suggestions regarding their behavior in the animal 

 organism. The relations of most nucleic acids, on the other hand, are 

 as we have already stated, not so clear, because they have not all 

 been studied in the same way, nor with the same care. Above all we 

 have no means for deciding which cleavage-products are to be regarded 

 in any given case as primary or secondary. Inosic acid is an excep- 

 tion, as its composition has been established, and we are justified in con- 

 sidering it as a simple substance. Perhaps this is also true of guanylic 

 acid l isolated by Bang and Raashon 2 from the pancreas. In the break- 

 ing down of this nucleic acid, guanine is the only purine base that could 

 be detected in the presence of phosphoric acid and a carbohydrate. As 

 to whether the remaining nucleic acids are simple substances or mixtures, 

 we have no means of knowing. It will be best here to mention merely 

 the most important nucleic acids. They are almost always designated by 

 the name of the organs from which they were obtained. 



The nucleic acids from the spermatozoa have been longest known. 

 Since F. Miescher 3 first called attention to them, they have been the subject 

 of frequent investigation. 4 It appears that the nucleic acids obtained 

 from the various kinds of spermatozoa are closely related to one another. 

 Certain observations indicate a far-reaching similarity. Great care should 

 be taken, however, in drawing any conclusions regarding the identity of 

 the various nucleic acids from analytical values or knowledge of the 

 cleavage-products. According to the grouping of the cleavage-products, 

 many differences may appear which are as yet hidden from our view. It is 

 noteworthy that the percentage of phosphorus present in the nucleic acids 

 isolated from the cells of ripe semen is, in general, a very constant one. 

 The values range between 9.11 per cent and 9.62 per cent. Salmon 

 nucleic acid, according to Schmiedeberg, 5 has the following composition: 

 C, 37.42 per cent; H, 4.19 per cent; N, 15.24 per cent; and P, 9.64. All 

 the known purine bases have been obtained in the cleavage of the 

 spermatozoa nucleic acids. The values are given on the following 

 page. 



1 I. Bang Z. physiol. Chem. 26, 133 (1898-99); 31, 241 (1900-01). 



2 I. Bang and C. A. Raaschon: Hofmeister's Beitr. 4, 175 (1903). 



3 F. Miescher: Verb, naturf. Gesell. Basel, 6, 138 (1874). Cf. also the complete works 

 of F. Miescher: loc. ciL 2, 55; Arch, exper. Path. Pharm. 37, 100 (1896). 



4 R. Burian: Ergeb. Physiol. 3, 1, 48 (1904). 



O. Schmiedeberg: Arch, exper. Path. Pharm. 43, 57 (1900). 



