BLOOD SERUM. 267 



carried down by the euglobulin, while the others are carried down by 

 the pseudoglobulin fraction. 



The non-protein organic constituents of the serum have been given 

 especial and careful study by E. LETSCHE l and he has found, besides the 

 previously known bodies, that the serum contains several acids, among 

 which there are two nitrogeneous acids whose nature has not been studied. 

 These, including other nitrogenous substances found by him, represent 

 a part of the so-called rest nitrogen, i.e., that nitrogen which remains in 

 the serum after the complete removal of the coagulable proteins. As 

 representatives of the bodies occurring as rest nitrogen in the serum we 

 must in the first place mention urea, also creatine, carbamic add, ammonia > 

 hippuric acid, phosphocarnic add (PANELLA), traces of indol (HERVIEUX),. 

 perhaps also uric add found by ABELES 2 in human blood, while LETSCHB 

 could not find any in horse-blood. 



According to BROWINSKI proteic acids (see Chapter XIV) occur in 

 the serum and CZERNECKI S has investigated the quantity of proteic 

 acid nitrogen in serum and transudates under different conditions. The 

 occurrence of proteoses is, as above mentioned, somewhat disputed. 

 We have several investigations on the occurrence of amino-acids (v. 

 BERGMANN, HOWELL, LETSCHE, ABDERHALDEN and others) which make 

 the occurrence of these very probable, and recently BINGEL has been able 

 to show the presence of glycocoll in normal ox-blood. Otherwise the 

 amino-acids have often been sought for in normal blood but in vain; 

 still recently certain investigators like VAN SLYKE and MEYER 4 have 

 shown the presence of amino-acids in the blood under normal con- 

 ditions. In dog blood after 24 hours' starvation they found 3-5 milli- 

 grams of amino-acid nitrogen in 100 parts blood. Under pathological 

 conditions lysine (NEUBERG and RICHTER 5 ) , leudne and tyrosine have 

 been found. Also purine bases and bile adds have been found in the 

 serum under pathological conditions. That the quantity of rest nitro- 

 gen is larger during digestion than in starvation requires further con- 

 firmation. 6 



1 Zeitschr. f . physiol. Chem., 53. 



2 Panella, cited in Virchow's Jahresb., 1902, 150, Hervieux Compt. Rend. soc. 

 biol., 56; Abeles, Wien. med. Jahrb., 1887. 



3 Browinski, Zeitschr. f. physiol. Chem., 54 and 58; Czernecki, Maly's Jahresb., 

 39 and 40. 



4 v. Bergmann, Hofmeister's Beitrage, 6; Howell, Amer. Journ. of Physiol., 17; 

 Letsche, 1. c.; Abderhalden, Zeitschr. f. physiol. Chem., 72; Bingel, ibid., 57; D. 

 v. Slyke and Meyer, Journ. of biol. Chem., 12. 



5 Deutsch. med. Wochenschr., 1904. 



6 v. Bergmann and Langstein, Hofmeister's Beitrage, 6; Hohlweg and Meyer, 

 ibid., 11. 



